SAN FRANCISCO, United States (AFP)—A huge electricity outage hit San Francisco on Saturday, leaving 130,000 residents without power for several hours at its peak, with the city’s main provider saying all services would return overnight.

Pacific Gas & Electric Company said in a statement on X that power had been restored to about 90,000 households by 9 pm Saturday (0500 Sunday GMT), “with the remaining 40,000 customers expected to be restored overnight.”

Large parts of the West Coast tech hub, which has a population of more than 800,000 people, were plunged into darkness, with disruptions to public transport and many traffic lights not working on a busy Christmas shopping weekend before power began to be restored.

“I know this was a rough day,” San Francisco Mayor Daniel Lurie said in a video posted on X from the city’s emergency operations center.

“That is progress (on restoration of power)… but for those of you who do not have power, we want to make sure you stay safe, check on your neighbors,” he said.

Lurie said police, fire department and other city officials had been sent out and asked residents to stay home if possible.

Many traffic signals were out, leaving traffic police to manage intersections and the self-driving ride-hailing service Waymo had paused operation of its vehicles, he said.

A fire at a substation had caused the blackout, Lurie said.

Parts of the city were blanketed in fog and many businesses were forced to close for the day at the height of the holiday shopping period, the San Francisco Chronicle newspaper reported, leaving normally bustling commercial areas quiet.

The abrupt fall in shoppers just days before Christmas was “devastating” for business, a manager of Black & Gold home goods store, told the San Francisco Chronicle.