A hero motorcyclist tried to stop the terrorist careering down the packed boulevard in Nice by climbing into the lorry's cab, a witness told The Telegraph, reports Lydia Willgress in Nice. 

The unnamed man was seen riding alongside the vehicle as it picked up speed, before trying to grab hold of the cab's door.

He desperately tried to get into the lorry to stop the attack as it travelled at more than 70km per hour, but horrified witnesses said he lost his grip and instead got sucked under the lorry's tyres.

Meanwhile, around six police officers with rifles were seen firing at the side of the lorry as it sped past them.

Michael Zarzycki, 64, who is staying in the Hotel Westminster with his wife Heather, also 64, witnessed the attack from his fifth floor balcony.

"There was a motorcyclist who tried to get up to him, other people in the hotel said he was tugging at the door.

"They were driving alongside each other. The motorcyclist was trying to get up near the cab but he did not have a good enough grip and then he fell and was dragged below the tyres. He wouldn't have survived."

It is understood the motorcyclist fell just before the lorry reached Hotel Westminster. 

Mr Zarzycki, a glasses salesman from Vancouver, Canada, said the lorry drove down the pavement next to the water before deliberately ploughing into a group stood on a zebra crossing. 

The Eiffel Tower is to glow red, white and blue for three days in tribute to the victims of the Nice massacre during a 72-hour period of national mourning, the Paris town hall has announced, Henry Samuel reports.

The landmark will be lit in France's national colours each night at 10.30pm (9.30 BST) to honour those who died.

Anonymous has posted a video threatening to do "all that is necessary" to stop those responsible for the Nice attack.

The hacker group, known for its cyber attacks against controversial organisations and individuals, has previously vowed war on terrorist group Islamic State for its co-ordinated attacks elsewhere in the country, including the November 2015 Paris attacks.

According to L'Express newspaper, the first victim to die was a Muslim mother of seven who wore a veil.

Fatima Charrihi's son Hamza said she was with nieces and nephews when she was killed, and that his brother had tried to revive her but she had died instantly.

He said: "She wore the veil, practising an Islam of the middle ground. A real Islam. Not that of the terrorists."

L'Express published a photo of her residence permit.

Her son added: "She was the first victim, there were no other bodies before her."

People in French embassies and at Bastille Day events sung poignant renditions of the French National Anthem,  La Marseillaise, as the news of the terror attack in Nice broke.

People on social media have also been sharing a clip from the 1942 film Casablanca as a way to pay tribute to those affected by the terror attack at Bastille Day celebrations in Nice. 

In the scene, the characters belt out La Marseillaise to drown out the Nazi officers' singing. ​  

National Front leader Marine Le Pen looked set to inflame tensions after posting on Twitter: "The war on the scourge of Islamist fundamentalism has not begun. It is urgent now that it be declared"

Fears are growing for a Scottish couple who are in holiday in Nice and have not been heard from since the truck attack.

Carol Annie Cowan, 27, and 30-year-old Ross Cowan, were in the French Riviera capital when the attacker struck.

The pair, from Helensburgh, Argyll and Bute, have not been heard from since.

Mrs Cowan's sister Amy Stanton posted a worried status on Facebook: 

 She told the Daily Record: “We are all just desperately hoping that they will get in touch. We have been trying to phone but their mobiles are not connecting and they haven’t posted on Facebook or anything like that.

“The whole family just desperately want to hear that they are ok. The longer that goes by without them getting in touch, the more worried we are all becoming.”

Downing Street has said a "small number" of Britons were injured in the attack in which a terrorist drove a truck through crowds.

UN Secretary-General Ban Ki-moon condemned the Bastille Day attack, calling for intensified efforts to confront terrorism and violent extremism.

Ban "stands firmly behind the French government and people as they confront this threat and stresses the need to intensify regional and international efforts to combat terrorism and violent extremism," a UN statement said.

French President Francois Hollande has revealed that around 50 people are in a critical condition "between life and death" after a lorry ploughed into crowds in Nice.

"As I speak 84 people are dead, and around 50 are in a critical condition between life and death," he said after visiting a hospital in the French Riviera city.

President Hollande said that "many foreigners" were among those killed or injured.

"There are French among the victims and also many foreigners from every continent and many children, young children," said Hollande in a speech from the hospital.

Mohamed Lahouaiej Bouhlel's estranged wife is in police custody, reports David Chazan.

Officers are questioning her about the Nice attacker's alleged Islamist links.

The 31-year-old truck driver was not on a terrorist watch list or suspected of being security threat, it has been reported.

Nader El Shafei, who witnessed the Nice attack, is reduced to tears as he shares his account of what happened in the terrorist attack last night. 

Matthew Holehouse in Brussels reports that Belgium will increase security for next week's national day celebrations after the truck attack in the French city of Nice on Bastille Day, said Charles Michel, the Prime Minister.

"We are determined to show that democracy is stronger than the terrorists," Mr Michel said. 

"We of course intend to take extra measures for events linked to the national holiday (on July 21)".

Belgium's terrorist threat level is at its second highest level of three, following deadly suicide attacks on the airport and metro network in March. 

Belgian authorities had previously anticipated a possible truck-style attack before the Nice carnage, in which at least 84 revellers were killed, Mr Michel added.

"Without revealing our plans, we were already wary to the idea of this type of scenario," Michel said.

Dr Shuja Shafi, secretary-general of the Muslim Council of Britain, said the attack was designed to "sow division" between communities. He said:

"I condemn utterly the violence once again meted out on the people of France. They have endured blood and carnage and it follows weeks of bloody outrage around the world, including in Muslim countries.

"Whatever twisted motives these people claim to be murdering for, it is quite clear these atrocities are designed to sow division, and create hatred and distance between communities. We cannot let them succeed.

"My thoughts and prayers are for the families of the victims and the wounded."

A number of tributes to the victims of the Nice attack have been left at the French embassy in London.

Bunches of flowers, a scarf bearing the country's name, and a note with signatures and a message in French which reads: "All my condolences to the families of the victims of the attacks of July 14 2016", have so far been placed on the steps of building. 

More than 30 foreign students aged about 14 also visited - lighting tealights and placing them in the shape of a peace sign.

Laurence Olding, from London, broke his wrist in the attack when he leapt over a wall with his fiancee to get away from the oncoming truck which he said was travelling at "30 or 40mph".

"We had been enjoying the firework display on the Promenade des Anglais - we came last year as well, and it's a wonderful occasion. All ages there, all nationalities, all races - everybody having a great time.

"The firework display had just finished and we were actually just heading back to our apartment.

"We just stopped to enjoy one of the bands that was playing on the promenade and then we heard lots of commotion and shrieking and shouting and then we saw a truck coming down the promenade, probably at 30 or 40mph - careering from side to side, obviously everybody was running and we were very concerned about this.

"We didn't know what to do and so we turned around as everybody else did - it got quite close to us and we decided to jump over the wall of the promenade and landed on the concrete which is a bit further down than I had anticipated, hence my wrist, but we were very lucky."

Mr Olding told Sky News his fiancee, Catherine, cut her leg in the incident.

"I was concerned that the truck might come over the wall at that point, so I think we were both running on adrenaline."

Once over the wall and on the beach, he said there was a sense of panic and he could hear gunfire, so the couple started running and made their way back to their apartment.

A barman was just 10ft from the bloody carnage in Nice as he watched a truck driver plough through men, women and children.

Robert Greene, from Coolock in Dublin, saw one man's body torn in pieces on the Promenade des Anglais as a woman cried over him, while the shattered remnants of a child's bike were strewn across the road.

The 33-year-old had just got off a bus with a group of friends as the Bastille Day celebrations and firework display drew to a close. 

Mr Greene said of the truck driver's progress:

"He came behind us and beside us as he was cutting through people. He was as close as 10ft away. I saw this truck and he cut through three or four people, he was already missing the bumper. It was horrific."

Some of Mr Greene's friends ran down a flight of steps to the beach below the promenade as the driver weaved along the road with the lights of the truck off, running over people indiscriminately.

Still in deep shock after witnessing the deaths, he described the carnage the truck left in its wake:

"A woman dropped to her knees, someone in her family had been killed, just lying there. There was not even a thing anyone could do, there was no CPR, bits of him were lying around.

"It was horrific. There was a young child's plastic tricycle, smashed up and left in bits.

"I stayed on top of the stairs looking around. It was surreal. People screaming, children crying, young children running around the place alone, a woman on roller blades screaming for her child. She found him."

Mr Greene arrived in Nice in the middle of May to work in Ma Nolan's Irish bar and to soak up the atmosphere at Euro 2016.

He was returning to the city with friends after a pool party at a hotel on the outskirts of Nice and said he thought the attack began close to where his group had got off the bus.

"There was no noise. He came in between us and the beach. I remember turning around and then hearing noise but there wasn't a huge amount of noise. We must have been close to the start.

"It doesn't seem real. When it was happening I remember thinking: why is he not stopping? He was starting to come closer. Then he started to veer in and veer out.

"I was not really looking at the driver at the time. I was more fixated on the truck and the people, the bumper was gone. That's when I thought, he's not just going to stop, this isn't an accident, he was ploughing into people. His lights were out. There was no noise."

The group took refuge in the Neptune restaurant on the beach where mattresses were thrown up against the walls and windows.

Staff and patrons watched reports of the attack on news channels for an hour and a half before firefighters came and gave them an escort across the Promenade.

David Blair, The Telegraph's chief foreign correspondent explains why France is being targeted following the terror attack in Nice. 

The Pope said on his official Twitter account: 

A statement released by the Vatican said: "We join in solidarity with the suffering of the victims and of the entire French people this day that should have been a great holiday.

"We condemn in the strongest way every demonstration of senseless violence, of hatred, terrorism and any attack against peace."

Mohamed Lahouaiej Bouhlel was recently estranged from his wife who now lives nearby, neighbours have told The Telegraph's Tom Morgan.

One said he was a "loner who was rude."

A neighbour who gave her name only as Jasmine, 40, said: "He was rude and bit weird. We would hold the door open for him and he would just blank him.

"He kept himself to himself, but would always rant about his wife. He had martial problems and would tell people in the local cafe.

"He scared my children though. They will be scarred by this. They were down there last night - they are 13 and 7 - they could have been involved."

She added: "He was very smart with the same haircut as George Clooney."

His neighbour - who lived next door - and didn't want to be named, said: "To be honest I hardly ever saw him.

"He was well dressed, and the last time I saw him he was with two other guys. I can't remember when it was."

Tunisian radio station Jawhara FM, based in Sousse, says Bouhlel is believed to come from a town close to Sousse called Msaken and has not travelled back to Tunisia in four years.

BFM TV reports that he was a divorced father-of-three who had become depressed following the breakdown of his marriage, reports Camilla Turner.

He was known to the police for assault with a weapon, domestic violence, threats and robbery but had no previous convictions for terrorism.

Neighbours told the French television channel that he was not particularly interested in religion, adding that he preferred girls and salsa.

They said that he had been unhappy since he divorce, and that he suffered from financial problems. He was a delivery driver, but recently caused an accident after falling asleep at the wheel and was taken into custody following the incident.

Police identified him through a driver’s licence in the truck, as well as fingerprints in the vehicle’s interior. Investigators also seized a mobile phone and credit cards from the truck.

New witness accounts of the Nice attack have emerged, describing what happened after the lorry ploughed into crowds of people.

Police in the UK are reviewing security at large-scale events planned over the next seven days including a number of music festivals, the Prime Minister's spokeswoman has said, Kate McCann reports.

Speaking to journalists this lunchtime, she confirmed that security will be reviewed and checked to ensure all the necessary arrangements are in place, this is not in relation to any specific UK-based threat but in the wake of the Nice attack. 

It follows an emergency meeting of Cobra this morning led by the Deputy National Security Advisor Paddy McGuinness in which security experts agreed that the UK threat level should remain the same, severe.

A small number of British nationals have been injured in the attack but no further details were available.

A consular team of eight people were deployed from the UK to France overnight and a further four are on the way as well as Julian King, the French Ambassador. 

Additional investigative support has been offered to the French and British Police liaison officers are on the ground. 

Police have carried out a controlled explosion on a white box van 50 metres down the road from Bouhlel's apartment, reports Tom Morgan.

 The explosive was set off shortly before 1pm as armed officers gained entry to the vehicle, said locally to be rented. 

The Bastille Day killer was described as a "loner with a motorbike" by neighbours as police searched his one bedroom apartment in a rundown district of Nice, reports Tom Morgan.

One resident in the small apartment block where Mohamed Lahouaiej Bouhlel is thought to have plotted his attack said: "He was quiet and moody. I did not know whether he was a Muslim. I think he had a motorbike."

Police sealed off a flat of La Route de Turin and ordered The Telegraph to step away from the scene.

Bouhlel, 31, is believed to have been living in a rented property overlooking a small carpark.

Colin Randall also reports from Route de Turin:

Police investigating the attacker's background raided a first floor flat in a shabby apartment block in the Abattoirs area of Nice.

A woman living in the same block said: 'I hardly knew him, but from what I could see he seemed very weird. He lived alone. He said very little to anyone and wasn’t very polite. He wouldn’t hold the door open for you.' 

The name of the flat occupant appears on the ground floor letterbox grid as Lahouaiej Bouhlel, though this name has not yet been officially confirmed as that of the 31 year old French-Tunisian attacker.

A schoolboy who also lives in the block of flats said he was alerted to the start of the raid at about 9.30am local time when armed police set up positions in front of the building and behind.

Two-and-a-half hours later there was still a strong police presence in the area and searches were understood to be continuing.

London's French ambassador has said the massacre in Nice was an attack on liberty, equality and fraternity.

Sylvie Bermann spoke on the steps of the embassy in Knightsbridge, where people have begun leaving tributes to the victims.

She told reporters: "The 14th of July (Bastille Day) is a very symbolic day - it is a symbol of liberty, egality and fraternity and I think that is what the terrorists also want to fight."

She also revealed that Foreign Secretary Boris Johnson attended a dinner to mark Bastille Day at her residence on Thursday night.

Ms Bermann said: "I would like to thank the British authorities because they expressed their sympathy and solidarity."

France's dedicated terror alert application for smartphones - which launched on June 8 at the start of the Euro 2016 tournament - took "two-and-a-half-hours" to register the Nice attack, according to Le Monde, reports Henry Samuel. 

The app is supposed to alert residents in case of attack according to their location and that of their friends/relatives.

Prime Minister Theresa May has said Britain stands "shoulder to shoulder" with France after the "horrifying" terror attack in Nice.

Mrs May insisted Britain must redouble its efforts to defeat "brutal" terrorist murderers, as she called a meeting of senior officials in the Government's emergency Cobra committee to see what Britain can do to help.

Speaking ahead of a visit to Scotland, the Prime Minister said:

"I have asked my deputy national security adviser to chair a Cobra meeting of senior officials to review what we know and what we can do to help and I will speak to President Hollande today and make clear that the United Kingdom stands shoulder to shoulder with France today as we have done so often in the past.

"If, as we fear, this was a terrorist attack then we must redouble our efforts to defeat these brutal murderers who want to destroy our way of life.

"We must work with France and our partners around the world to stand up for our values and for our freedom."

Mrs May said the Government was working to establish whether any British nationals were caught up in the attack.

"Our hearts go out to the French people and all those who have lost loved ones or been injured," she said.

"While the full picture is still emerging, it seems that at least 80 people are feared dead and many others have been injured.

"It was innocent victims enjoying a national celebration with their friends and families.

"We are working urgently to establish whether any British nationals were caught up in the attack.

"Our ambassador is travelling to Nice today with consular staff and they will be doing all they can to help anyone affected."

The French Embassy has lowered its flag as a mark of respect to those who died during last night's terrorist attack in Nice.

On Friday morning two armed policemen were drafted in from Heathrow to stand outside the embassy as an extra security measure.

At roughly 7.30am the embassy in central London chose to lower the French flag and the European flag as a mark of respect - as has been done in Downing Street. 

John Woodcock, MP for Barrow and Furness, is currently in Nice and was on the seafront when the attack was carried out. He tweeted:

"We were very fortunate - we left the promenade as soon as the fireworks finished," he told the BBC.

"We first sensed something was wrong when lots of people were running past us and (saw) sirens in the opposite direction."

He added that he did not realise the "full horror" of what had happened until later.

Witness Eric Ciotti told Europe 1 radio of the horrifying moments people fled to safety - with some running into the sea in a desperate attempt to flee.

He added: "A person jumped on to the truck to try to stop it.

"It's at that moment that the police were able to neutralise this terrorist. I won't forget the look of this policewoman who intercepted the killer."

Egyptian Nader El Shafei told the BBC he saw the driver "looking very nervous".

He said: "I kept yelling at him, waving with my hands to stop and trying to tell him that there is a lot people under his truck - dead already. But he did not give any attention to anyone outside the truck.

"And suddenly I saw him picking up something like a cellphone. I thought he would call the ambulance for the accident but it seemed that I was wrong, because he just picked up his gun and he started to shoot the police.

"Just when they (the police) arrived they just felt something was wrong so they kept yelling at him and when he did not step out - they saw him from the window taking his gun out.

"They knew that would be a gun shooting so they just killed him right away - they did not wait to negotiate or something, they just opened fire on him."

British Airways has pledged to do "everything we can" to help concerned passengers due to travel to or from Nice, after a lorry was driven into a crowd in the French city.

People due to fly in the next few days will be able to fly on a different date or to a different destination.

A spokeswoman for BA said: "Following the tragic events in Nice we are contacting customers to give our support and offer to change their flight if they wish.

"We'd encourage customers in Nice to get in touch with us if they want to make a change to their booking and we will do everything we can to help.

"For customers booked to travel to Nice in the next few days we are offering to change their booking to an alternative date or destination.

"We'll continue to be as flexible as possible to help our customers. Our deepest sympathies are with the loved ones of the victims."

Travel trade organisation Abta urged holidaymakers already in Nice to follow updates on the situation.

Rob Wainwright, director of Europol, said: "This attack is yet another reminder of the active terrorist threat we face in Europe.

"Europol stands in full solidarity with the citizens of France, as it does with all victims of terrorism, and has made available to the French authorities the full operational capabilities of the European Counter Terrorism Centre."

Former prime minister David Cameron condemned the "sickening and dreadful attack" on Twitter:

Shadow home secretary Andy Burnham was among the other politicians to react on Twitter: 

Labour leadership hopeful Angela Eagle also shared her support on Twitter:

Mohamed Lahouaiej Bouhlel - a 31-year-old career criminal who was born in Tunisia before moving to France - has been named as the Nice truck attack suspect by local news website Nice-Matin.

It reports that the delivery driver is the owner of the identity card that was found in the truck by police.

Tour de France security measures have been stepped up for Friday's 13th stage following the Nice attack.

Some 600 security forces have been deployed on the 37km-long stage 13 route from Bourg Saint Andeol to La Caverne du Pont d'Arc in the south of France.

Riders including race leader Chris Froome sent messages of support, posting a picture of the blue, white and red French flag on Twitter:

The children's hospital in Nice says it has treated some 50 children and adolescents injured in the truck attack, including two who died during or after surgery.

Stephanie Simpson, the communications director for the Lenval foundation hospital, said that injuries included fractures and head injuries.

In a phone interview, she said: "Some are still life and death." She said she could not say exact number of children hospitalised or the ages of those who died.

The hospital is also offering psychological counselling to parents and siblings.

London Mayor Sadiq Khan has announced he will be "reviewing our own safety measures" in light of the attack in Nice.

He declared that the capital would "stand united" with France and insisted the "poisonous and twisted" terrorists would be defeated.

Speaking on a visit to Gatwick Airport, Mr Khan said: "I will reassure all Londoners that today we will be reviewing our own safety measures in light of this attack and that I and the Metropolitan Police Commissioner will do everything possible to keep Londoners safe."

Christian Estrosi, the regional president in Nice, said at least 10 children are among the dead - and the death toll is expected to rise.

He said some of the city's 1,200 security cameras had pinpointed the moment the attacker boarded the truck, far from the seaside "in the hills of Nice" and could follow his path to the promenade. Estrosi called for the investigation to focus on any accomplices.

"Attacks aren't prepared alone. Attacks are prepared with accomplices," Estrosi said. "There is a chain of complicity. I expect it to be unveiled, discovered and kept up to date."

France has declared three days of national mourning after the terror attack in Nice, French Prime Minister Manuel Valls has said.

Speaking after an emergency meeting, he said the national mourning would begin on Saturday. He confirmed that a measure extending the country's state of emergency would go before lawmakers next week.

Valls and French President Francois Hollande are going to Nice later Friday.

Bastille Day, which celebrates the storming of the Bastille prison in Paris during the French Revolution of 1789, is the country's biggest public holiday. 

The UK threat level from international terrorism remained unchanged on Friday morning at "severe", reports Ben Farmer.

The level, which currently means an attack is deemed "highly likely" has remained unchanged since October 2012.

An American father and son on a dream trip to the South of France were among the victims killed in the Nice terror attack, according to friends and family.

Sean Copeland, 51 and his 11-year-old son Brodie from Austin, Texas, had been on holiday when the lorry was driven into crowds. 

Confirming the deaths, his niece, Hayley Copeland wrote on Facebook: “This is an extremely difficult time for my family and anyone who knows Sean and Brodie Copeland.

"Losing a loved one is hard no matter the circumstances but losing a loved one in such a tragic and unexpected way is unbearable. Prayers are much appreciated.”

Chinese president Xi Jinping strongly condemned the attack in Nice in a phone call with French President François Hollande,  China Correspondent Neil Connor reports from Beijing.

Mr Xi expressed to his French counterpart "strong condemnation to this shocking, brutal act, sent deep grievances to the dead, as well as sincere condolences to the injured and family members of victims," Chinese reports said.

"China firmly opposes terrorism in any form," the Chinese president added. Li Keqiang, China's prime minister, expressed "deep mourning" for the dead.

China's number two official also sent "sincere condolences to the injured and family members of victims."

Chinese Foreign Minister Wang Yi said: "The Chinese people stand in firm solidarity with the French people."

Meanwhile, authorities confirmed that two Chinese nationals were injured in the attack.

Investigators are searching the home of the driver of the lorry in the Abattoirs area of Nice, reports Jannat Jalil in Toulouse.

At least one British national is among those injured in the attack in Nice, France, Foreign Secretary Boris Johnson has said.

He said "our thoughts are very much with the people of France and Nice" after this "absolutely appalling incident".

French President Francois Hollande has sthe country's state of emergency would be extended for another three months.

He said the country's borders were being tightened, as he vowed that France would show "real force and military action in Syria and Iraq". 

The Foreign Office has updated its travel advice to Britons around Nice, advising them to stay indoors, reports Ben Farmer.

It said: "We are in touch with the local authorities and seeking more information following an apparent attack on Bastille Day celebration in Nice.

"If you are in the area follow the instructions of the French authorities who are at present advising people to stay indoors at this time."

Justin Welby, the Archbishop of Canterbury, asked people via Twitter to pray for Nice:

A Russian woman was killed and her friend hurt in the Nice attack, Russian news agencies said on Friday, quoting Irina Tyurina, spokeswoman for the Russian Union of Travel Industry. Ms Tyurina said she got the information from insurance agencies.

"Two friends from Russia were taking a walk on the Promenade des Anglais. One was killed by the truck, the other lightly injured, she's got broken toes and some other minor injuries," Ms Tyurina said.

Thousands of Russian tourists are estimated to be holidaymaking in Nice.

Christian Estrosi, the regional president in Nice, said some of the city's 1,200 security cameras had pinpointed the moment the attacker boarded the truck, far from the seaside "in the hills of Nice" and could follow his path to the promenade. Mr Estrosi called for the investigation to focus on any accomplices.

"Attacks aren't prepared alone. Attacks are prepared with accomplices," Mr Estrosi said. "There is a chain of complicity. I expect it to be unveiled, discovered and kept up to date."

Mr Estrosi said more than 10 children were among the dead and he said France needed to think carefully about its next response to attacks, as previous responses were not enough to protect the people.

The Labour leadership candidate has cancelled his scheduled campaign launch today in light of the attack.

Russian President Vladimir Putin sent a message of condolences to his French counterpart Francois Hollande over mass killings in the French city of Nice, Kremlin spokesman Dmitry Peskov has said.

American witness Kayla Repan has described the moment the attack began and she and her fiance ran for safety.

President Francois Hollande and Prime Minister Manuel Valls are going to Nice today.

Christian Estrosi, the president of region and former mayor of Nice, has questioned the readiness of security forces, saying insufficient forces had been deployed.

Read how the attack unfolded here.