A massive outage knocked out power to 130,000 homes and businesses in San Francisco on Saturday, Pacific Gas and Electric Co. said.

The power failure left a large swath of the northern part of the city in the dark, beginning with the Richmond and Presidio neighborhoods and areas around Golden Gate Park in the early afternoon and growing in size.

PG&E did not immediately respond to requests for comment on the cause of the blackouts. The outage represents roughly one-third of the utility company’s customers in the city.

Social media posts and local media reported mass closures of restaurants and shops and darkened street lights and Christmas decorations.

The San Francisco Department of Emergency Management said on X there were “significant transit disruptions” happening citywide and urged residents to avoid nonessential travel and treat down traffic signals as four-way stops.

The city’s transportation agencies said they were bypassing some Muni bus and BART train stations because of the power outages.

At least some of the blackouts were caused by a fire that broke out inside a PG&E substation at 8th and Mission streets, fire officials posted on X at about 3:15 p.m.

At about 4 p.m., PG&E posted on X that it had stabilized the power grid and was not expecting additional customer outages. The company said it was unable to confirm if power would be restored by later Saturday.