SAN FRANCISCO (KGO) -- Power was restored for thousands more PG&E customers on Sunday afternoon, but under 12,000 customers were still without electricity as of PG&E's latest update Monday morning.
PG&E said it would open a resource center in the Richmond District, one of the areas still without power Sunday, at 251 18th Avenue, that will be open from 5 p.m. to 10 p.m. It will offer snacks, drinks, Wi-Fi, and charging stations.
A PG&E spokesperson, Andria Borba, said in a video posted on X that power was estimated to be restored by 2 p.m. Monday for those remaining customers, which were mostly on the city's west side, Golden Gate Park and the Presidio, along with patches of blocks downtown.
The resource center will be open again Monday from 8 a.m. to 10 p.m. "if needed," according to the company.
In a message from Mayor Daniel Lurie, echoed PG&E's update and urged residents to make preparations.
"Which means if you do not have power now, you should not expect to get power until (tomorrow). So plan for it," Lurie said said in a social media video. "Let's get get prepared. Let's do it now, before night time comes."
About 130,000 customers lost power Saturday afternoon after a fire broke out at a PG&E substation in the SoMa District, causing "significant damage," according to the utility company.
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About 95,000 customers had their power restored by 11 p.m. Saturday, and more overnight, but about 21,000 were still in the dark as of Sunday morning, according to PG&E.
No injuries were reported in the fire at the substation at 8th and Mission Streets.
The damage was called "significant," in a statement from the company shared by spokesperson Edgar Hopida.
The statement said the utility was working on creating extra power generation at other substations in the city and said repairs to the substation in SoMa would be complicated.
"This is a very complex work plan and will require the highest amount of safety focus to ensure safe work actions," PG&E's statement said.
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The company also said it was working with the 211 Providers Network to conduct wellness checks of customers by knocking door to door and said anyone in need of assistance should call 211.
PG&E said it would provide food assistance and hotel vouchers for customers left vulnerable by the outage through the Disability Disaster Access & Resources program offered by the California Foundation for Independent Living Centers, a nonprofit advocacy organization that PG&E sponsors.
Borba said PG&E activated its Emergency Operations Center in Vacaville to respond to the San Francisco outage and the ongoing storm. She said crews were pre-positioned Sunday in anticipation of rain that was forecast to continue through Friday.
The large power outage in San Francisco on Sunday means that several city offices and other public buildings will be closed Monday, the Sheriff's Office said.
City Hall, the Main Library, the Civic Center Garage, Muni customer service on Van Ness Avenue, and offices at 525 Golden Gate, 101 Grove St., and 1 Van Ness Ave. will be closed Monday.
The War Memorial's Veterans Building and the Asian Art Museum will also not be open to the public without restoration of power, the Sheriff's Office said.

San Francisco Supervisors Connie Chan and Alan Wong released statements Sunday reaching out to their constituents and giving updates. Wong also called for a public hearing on what he said are repeat outages in his district, and to see why this weekend's blackout, which began at a PG&E substation fire, ended up spreading to affect almost one-third of the city, his office said.
"It's important that we fully understand what happened," said Wong in a statement from his office. "We still don't have a clear explanation for how a localized incident escalated into an outage affecting so many neighborhoods. This hearing is about getting answers, improving communication, and making sure residents and small businesses are better supported going forward."
Wong said he will propose the hearing at an upcoming Board of Supervisors meeting.
The massive outage happened on one of the biggest shopping days of the year, which was a big concern for San Francisco District 6 Supervisor Matt Dorsey, who represents the South of Market district.
"The Saturday before Christmas is historically one of the busiest shopping days of the year. We've got the Warriors game. We've got the ballet. We've got the symphony and everything going on. This is the worst time PG&E could have a problem," Dorsey said.
San Francisco District 5 Supervisor Bilal Mahmood said the city had been using all its resources to help PG&E restore power.
"This is unacceptable. I have never seen anything like this over the decade I have been here in San Francisco. There will have to be further investigation and questions that have to be answered about what went wrong," Mahmood said.
Dorsey said the same substation was responsible for a blackout on Dec. 21, 2003, affecting about 120,000 customers at the time.
There was rain forecast Saturday, but there was no indication if the weather played any role in the outage. More rain was forecast for Saturday evening and for the next six days. Wind gusts could reach up to 25 mph Saturday, according to the National Weather Service.
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Residents can get updates on Muni operations here.
Bay City News contributed to this report