Sporadic power outages cascaded across San Francisco on Tuesday afternoon, affecting widespread areas throughout the city, including the downtown financial district, and halting its famous cable cars on the city's steep hills.
About 51,000 electricity customers in San Francisco and an area south of the city were in the dark, but power was being restored by late afternoon, said Darlene Chiu, spokeswoman for Pacific Gas & Electric Co., the main utility for the city.
Chiu said the breakdown was triggered by a fault in PG&E's underground electric system but the utility did not know what caused the problem and it was investigating, she said.
Local radio station KCBS said the outages may been set off by an explosion in an underground electric fault on a downtown street.
More than 30,000 customers had electric service restored and all customers were expected to get their lights back on by about 4 p.m. PDT, two hours after the outages began.
Bay Area Rapid Transit commuter trains were moving, although some of the lights in underground stations were off, a BART spokesman told local radio.
In addition to the cable cars, some city bus services were disrupted in the North Beach and Chinatown tourist neighborhoods and downtown due to the failure of overhead power lines, a spokeswoman for the San Francisco Municipal Railway said.
The power outage could also be responsible for shutting down some of the Internet's major players. Several prominent websites including Craigslist, CNet, Technorati, Yelp and Red Envelope.
San Francisco-based classified site Craigslist was also down Tuesday afternoon, but founder Craig Newmark said he didn't know why. "Craigslist and many other sites are having issues at the colo facility. Please sit tight, and try again later. We are aware of the situation, and the happy craigslist elves are scurrying to make it better, even now," said an error message on the site's homepage.
Pacific Gas & Electric is owned by PG&E Corp. .