The city's residents took to social media to post about many closed restaurants and shops, unusual for this time of year before the Christmas holidays.

Known to be home to many of the US' biggest tech firms, San Francisco saw disruptions to public transport and traffic as a result of the outage. Authorities told people to stay at home and off the roads.

"We've got rain coming. It's night time. If you don't need to go out, stay home," San Francisco Mayor Daniel Lurie posted on X.

Lurie later posted that some services were resumed, but others remained impacted, continuing to urge residents to stay home.

Fire partial cause of outage
 

The city's main power provider, Pacific Gas & Electric Company, said it was working together with the authorities on restoring electricity supply. It later added that it stabilized the power grid and that no further outages were expected.

A fire at one of the company's substations appeared to be the cause for some of the blackouts, according to fire officials.

It was not immediately clear how long it would take for power to be fully restored.