Thousands remain without power in San Francisco the morning of Dec. 21 as the city recovers from a major power outage that was caused by a fire at a power facility the day before.

At its peak on Dec. 20, the outage plunged approximately 130,000 PG&E customers in San Francisco into darkness, according to SFGate and the San Francisco Chronicle, about 30% of the city.

The USA TODAY Power Outage tracker indicates that more than 22,000 customers remain without power, as of around 9:30 a.m. local time. The PG&E Outage page puts that same figure at around 21,000 as of just after 10 a.m. The majority of the remaining outages are located around the Presidio and Richmond neighborhoods.

"At this time, we are unable to provide a precise timeframe for full restoration but will provide additional detail and information as our assessment and repair efforts continue," PG&E said in an early Dec. 21 update.

The San Francisco Fire Department reported that it responded to a fire at a PG&E substation at 8th Street and Mission Street around 3:15 p.m. local time on Dec. 20.