Published Friday, April 21, 2017 | 10:33 a.m.
Updated Friday, April 21, 2017 | 11:54 a.m.
SAN FRANCISCO — A power outage struck a wide area of San Francisco on Friday, blacking out about 90,000 utility customers, snarling traffic as intersection signals went dark and stopping the famed cable cars for a time.
Pacific Gas & Electric crews were assessing the problem and there was no immediate estimate for restoration of electricity.
Media reports indicated that firefighters and utility crews were at a smoky fire at a substation, but there was no word on whether it was related to the outage.
"Power outage in the Northern & Central part of SF," the San Francisco Department of Emergency Management tweeted, urging the public to refrain from calling 911 unless it was a life-safety issue.
The outage affected the Financial District, including 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.
People milled on sidewalks, controllers directed traffic manually, and shops were dark. Some buildings had power, others did not. ATM screens were blank.
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."
The San Francisco Chronicle reported (http://bit.ly/2pN3o6b ) the outage also affected the Presidio, and KRON-TV reported effects stretched to the Marina/Cow Hollow area.
San Francisco has a population of about 850,000.