A massive outage has knocked out power to 130,000 homes and businesses in San Francisco. The outage Saturday represents roughly one-third of Pacific Gas and Electric Co's customers in the city. The power failure left a large swath of the northern part of the city in the dark, beginning with the Richmond and Presidio neighborhoods and areas around Golden Gate Park. PG&E did not immediately respond to requests for comment on the cause of the blackouts. Fire officials said at least some of the blackouts were caused by a fire that broke out inside a PG&E substation.