The power outage started just before 6 p.m. Saturday when a fire broke out at a major Pacific Gas & Electric Co. substation.
About 120,000 customers lost power, including parts of Mission, North Beach, Chinatown and downtown San Francisco, PG&E officials said. The outage forced early evacuations at theaters and shopping centers, restaurants closed early, and street lights stopped working, causing traffic problems throughout the city.
Officials expected to have power fully restored late Sunday morning, said PG&E spokesman Jonathan Franks. About 46,000 customers were still without power at dawn.
Engineers had restored power late Saturday to about half of the affected customers, but those customers were plunged back into darkness when workers discovered the fire had not been fully contained and the substation had to be shut down again.
The cause of the fire was under investigation, Franks said.
``There's no indication that it was vandalism or sabotage. As far as the exact cause, we just don't know yet,'' he said.
