At least four people were injured after a tornado struck northern California on Saturday afternoon, according to local authorities.
The twister flipped over several cars and brought down power lines in Scotts Valley, located around 55 miles (89km) south of San Francisco, police said.
The National Weather Service (NWS) said the tornado was categorised as an EF1, one of the weakest classifications, and that it lasted around five minutes.
Earlier on Saturday, residents of San Francisco had been issued a tornado warning for the first time ever as thunderstorms swept through the region.
In Scotts Valley, the tornado touched down at 13:39 local time (21:39 GMT) on Saturday, police said.
The local fire service said at least four people had been injured and at least two of them had been taken to hospital, BBC's US partner CBS News reported.
Police closed a road overnight to allow for repair work to be done and debris cleared.
Wind speeds were estimated to have peaked at around 90mph (145km/h), the NWS said.
The weather agency also said the twister had been around 30 yards (27m) wide and travelled for a quarter of a mile (400m) before subsiding.
Earlier on Saturday, a tornado warning was issued to residents of San Francisco just before 06:00 local time (14:00 GMT).
The warning was for parts of downtown San Francisco and northern San Mateo County.
More than one million residents were woken in San Francisco and its suburbs to alerts on their mobile phones, warning them to "take shelter now".
Winds of up to 60mph (96km/h) ripped through the area, the NWS said.
But a few minutes later, NWS Bay Area said the warning was over and the storm had moved out of the city's downtown.
The city last saw a tornado in 2005, though that struck without any clear radar signature, so no warning was issued in that case, NWS meteorologist Roger Glass told AP news agency.
Nearby San Mateo County was last issued a tornado warning in 2011.
The warning came after a powerful storm passed through overnight - trees were toppled and there were major power cuts.
As of Sunday, more than 50,000 customers were still without power along the northern and central California coast, according to the PowerOutage website.
NWS Bay Area warned that residents should steer clear of the seaside over the weekend, with a coastal flood advisory in place until Monday.
San Francisco's tornado alert came just a week after the city saw its first ever tsunami warning.
The brief advisory was issued for northern California and southern Oregon following a magnitude 7.0 earthquake that hit off the northern coast of the state.
It was later rescinded, and no injuries were reported.