Waymo suspended its robotaxi service in San Francisco on Saturday evening after a massive blackout appeared to leave many of its vehicles stalled on city streets.

Numerous photos and videos posted to social media captured Waymo robotaxis stalled at roads and intersections as human drivers were either stuck behind them or weaved around them.

Waymo said on Saturday that it had temporarily suspended service in the city due to the blackout. It wasn’t until late Sunday afternoon that Waymo spokesperson told TechCrunch in a statement that the company was resuming service.

“Yesterday’s power outage was a widespread event that caused gridlock across San Francisco, with non-functioning traffic signals and transit disruptions,” the spokesperson said. “While the failure of the utility infrastructure was significant, we are committed to ensuring our technology adjusts to traffic flow during such events.”

The Waymo spokesperson added that the company is “focused on rapidly integrating the lessons learned from this event, and are committed to earning and maintaining the trust of the communities we serve every day.”

Power outage took out the waymos RIP pic.twitter.com/DPte8oOGku — Vincent Woo (@fulligin) December 21, 2025

The blackout also took down many of the city’s traffic lights and affected Muni mass transit, with San Francisco Mayor Daniel Lurie warning residents to stay off the roads unless they needed to travel.

Waymo said that although its self-driving systems are designed to treat non-functioning traffic lights as four-way stops, the scale of Saturday’s blackout caused some robotaxis to remain stationary for longer than normal as they tried to assess the intersections. The company also said that the majority of active trips were completed successfully.

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The blackout appears to have been caused by a fire at a Pacific Gas & Electric substation in the city. SFGate reports that around 120,000 PG&E customers were affected by the blackout, and while the majority of them had power restored by late Saturday, 35,000 customers were still without power on Sunday morning. PG&E’s website also showed thousands of San Francisco customers still affected at that time.

A letter from Tiger Global Management that leaked earlier this month said Waymo is now providing 450,000 robotaxi rides per week, nearly double the amount that the Alphabet-owned company disclosed in the spring.

This post has been updated with Waymo’s statement that service is resuming.