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.

Elsewhere in the US, an ice storm swept into the Midwestern states of Iowa and Nebraska, heavy snowfall hit upstate New York, and severe weather warnings were issued around Lake Tahoe, which straddles the states of California and Nevada.

In Nebraska, at least one person was killed in a crash on an icy road near Arlington. Washington County Sheriff’s Office said a 57-year-old woman lost control of her pickup truck and crashed into an oncoming vehicle.

A major highway between Iowa and Nebraska, Interstate 80, was shut down as vehicles slid off the road due to the icy conditions. It has since reopened.

In upstate New York, people ploughed snow out of their driveways, with more than 33in (83cm) of snow reported near Orchard Park in Erie County.

To the west, in Nevada, up to 3ft of snow was predicted in the Sierra Nevada mountains.

Snow also hit areas around Lake Tahoe, with some ski resorts seeing more than 1ft.

A 112mph gust of wind was recorded at the Mammoth Mountain resort south of Yosemite National Park, the NWS said.

In California’s Scotts Valley, the tornado touched down at 13:39 local time (21:39 GMT) on Saturday, police said.

The local fire service said four people had been injured and two of them had been taken to hospital, the BBC’s US partner CBS News reported.

Wind speeds were estimated to have peaked at around 90mph, the NWS said.

The weather agency also said the twister had been around 30 yards wide and travelled for a quarter of a mile before subsiding.

Earlier on Saturday, a brief tornado warning was issued to residents of downtown San Francisco and San Mateo County just before 06:00 local time.

San Francisco 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.

As of Sunday, more than 40,000 customers were still without power along the California coast, with Monterey county the worst affected, according to the PowerOutage website.

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.