A massive power outage struck downtown San Francisco, leaving at least 88,000 PG&E customers without electricity, snarling traffic as intersection signals went dark and stopping the famed cable cars for a time.

PG&E officials said an overloaded circuit breaker malfunctioned at the Larkin substation, sparking a fire in the insulation. The fire caused a series of outages beginning at 9 a.m. PT and left thousands without power in a massive swath of the central city.

A massive power outage struck downtown San Francisco, leaving at least 88,000 PG&E customers without electricity, snarling traffic as intersection signals went dark and stopping the famed cable cars for a time. Jean Elle reports.

All power was restored to customers by 5 p.m., officials said.

The outages affected the Financial District and prompted the temporary closure of the Bay Area Rapid Transit's downtown Montgomery Station. People used the lights of their cellphones to walk through the darkened station before BART stopped service there.

[NATL-BAY] Power Outage Affects Thousands in San Francisco

According to PG&E, residents and businesses in Western Addition, Pacific Heights, Japantown, Polk Gulch, Russian Hill, Marina, Richmond, Presidio, Laurel Heights, Sunset, Chinatown, North Beach and Fisherman's Wharf also found themselves in the dark.

California Pacific Hospital and Saint Francis Hospital were in the affected area, but remained open by using backup generators. Public schools also were open, according to PG&E.

Missing Attachment PG&E said a series of outages began at 9 a.m. PT and within 30 minutes about 90,000 San Francisco customers lost power. The utility said it hopes to restore power by 1 p.m. for most people. Crews had restored electricity for an estimated 12,500 people by 12 p.m.

The San Francisco Fire Department said it has responded to more than 100 calls for service. However, no injuries related to the blackout were reported.

The department tweeted that the calls included 20 elevators with people stuck inside. The department added there have been no delays in responding to calls.

The SFMTA said in a tweet that people should treat intersections as four-way stops due to "scattered" power outages citywide. SFMTA warned commuters to expect delays, while Caltrain tweeted that their trains were still running on time.

People milled on sidewalks, controllers directed traffic manually, and shops were dark. Some buildings had power, others did not. ATM screens were blank.

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Social media posts indicated that the outage forced businesses to close. Some posted apologetic messages on their doors, while others closed their gates.

Famous Union Square steakhouse John's Grill said it was unable to to serve lunch for the first time since the 1989 Loma Prieta earthquake. Macy's and other stores were also closed.

Susan Dang, a manager of a doughnut and Vietnamese sandwich shop, said they would have to close unless they could get a generator.

“If there’s no power, I let my boss know already,” she said.

Employees at a Starbucks were giving out cups of iced and hot coffee in the darkened shop. A worker said that was better than letting the coffee go to waste.

Brent Chapman, who works in billing and reporting for First Republic Bank, told his team to go home after huddling on a sidewalk and waiting for word of when power would be restored.

His team had been ready to send out a finished project Friday, one they’d been working on for six months, after some had pulled an all-nighter.

“It’s brutal. This is seriously the worst possible time that this could have happened,” he said. “I do not want to leave. I want to stay and get this done.”

People were asked to refrain from calling 911 except for emergencies. Texting "AlertSF" to 888-777 will activate text alerts on people's cell phones.

They also acknowledged people's fears about a number of simultaneous power outages that were reported in other cities - including Los Angeles and New York City - but believe that the one in San Francisco was triggered by "equipment failure."