A massive power cut struck a wide area of San Francisco on Friday, blacking out about 90,000 utility customers.
The series of outages hit the city at 9am on Friday, said Tamar Sarkissian, a spokeswoman for Pacific Gas & Electric.
Crews were assessing the problem and there was no immediate estimate for restoration of electricity.
The cut also snarled up traffic as intersection signals went dark and stopped the famous cable cars.
Local media reported firefighters and utility crews were at a 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 is 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 mobile phones to walk through the darkened station before BART stopped services there.
The San Francisco Chronicle reported 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.
Pacific Gas & Electric said that it has restored electricity to 15,000 customers affected by the power outage.
In a statement posted on its website, PG&E said it expects to restore power to about 25,000 more customers “in the next few hours” and to remaining customers late in the afternoon.
PG&E has not said what caused the power cuts.