Bangkok, Thailand (CNN) -- A leader of anti-government protests in Thailand was shot in the head while being interviewed at the demonstrations, according to the journalist who was with him at the time.
Seh Daeng was in critical condition, according to his guards with the Red Shirt protesters.
Video footage taken just after the shooting showed Seh lying on the ground, dressed in camouflage, as frantic protesters attempted to move him and get help. Seh appears to be bleeding from a head wound. Footage from the hospital showed medics covering Seh's face as he was brought in on a stretcher amid a throng of media.
Tom Fuller of the International Herald Tribune told CNN he was interviewing Seh at the time of the shooting.
Witnesses said the gunshot appeared to come from a rooftop in a corner of Bangkok's Lumpini Park, where protesters have amassed.
While it was unknown whether Thailand's military or government was behind the shooting, the government has previously made it clear it would shoot at what it called armed terrorists.
A renegade Thai general, Seh, whose full name is Maj. Gen. Kattiya Sawasdipol, is one of the Red Shirts' most radical, hard-line leaders, said CNN's Dan Rivers.
Other, more moderate leaders of the organization, who had insisted the protests were peaceful, had sought to distance themselves from him.
Explosions and gunfire were heard near the site of the protests in Bangkok. One of the explosions came just after She's shooting, according to witnesses. It was not immediately clear whether the explosion stemmed from Red Shirt retaliation for the shooting.
The incident came after Thai authorities set a new deadline to seal off the Bangkok intersection where protesters have gathered by the thousands for the past month.
Officials said soldiers will seal off roads and shut down rail service leading to the Ratchaprasong intersection from 6 p.m. (7 a.m. ET) Thursday.
However, the road on the park's eastern border remained open as of about 8 p.m. (9 a.m. ET), Rivers said. He said he had seen few soldiers.
The United Front for Democracy Against Dictatorship (UDD), which has been leading the protests, greeted the announcement with defiance.
"We want peace but they want war. Come and get in," said Weng Tojirakarn, a party leader. "We will fight with our bare hands. We will stay."
Authorities had initially threatened to shut off power, cut supplies and seal off the intersection at midnight Thursday.
They postponed the plan because they wanted to limit the impact on area residents, said Panitan Wattanayakorn, the acting government spokesman.
The Centre for the Resolution of the Emergency Situation in Bangkok said it has now asked businesses in the area to shut down until the situation is resolved.
The government said it has been forced to take action after demonstrators disregarded an ultimatum by Prime Minister Abhisit Vejjajiva to vacate the intersection by Wednesday.
The UDD has turned the posh commercial center into a fortress of tires and bamboo sticks as they continued their demand that Abhisit dissolve the lower house of the parliament and call new elections.
The Red Shirts are supporters of former Prime Minister Thaksin Shinawatra, who was ousted in a bloodless military coup in 2006.
Spokesman Panitan said continuing protests by Red Shirts would affect the proposed election date of November 14.
He said Abhisit had mentioned that the proposed date for the new election had been made with the condition that the Red shirts stop their protests. "He never said he withdrew his proposal," Panitan said.
More than two dozen civilians and military personnel have died in police-protester clashes in the ongoing unrest.
Over the weekend, two Thai police officers were killed and eight people injured in violence that began Friday night and lasted into early Saturday.
CNN's Kocha Olarn contributed to this report