Media playback is unsupported on your device Media caption The town of Guerneville has been cut off by floodwater

Two towns in northern California's wine-making region have been turned into virtual islands by record-breaking floodwaters, say authorities.

Sonoma County authorities, about 70 miles (110km) north of San Francisco, said about 3,600 people were evacuated after the Russian River flooded.

Torrential rain and snowfall has triggered the worst deluge in over 20 years, emergency officials say.

The towns of Monte Rio and Guerneville are currently only accessible by boat.

Image copyright Getty Images Image caption Flooding also submerged the shopping district of the nearby town of Sebastopol

"You cannot get into or out of town," Sonoma County officials said on Wednesday night in a mandatory evacuation order. "Guerneville is officially an island."

Around 2,000 homes and businesses are currently underwater, Ms Khan said, adding that only around half of the town's 4,500 residents complied with the official warning to leave.

On Thursday, Governor Gavin Newsom declared a state of emergency in five counties experiencing flooding, mudslides, and damage to criminal infrastructure from the storms.

A hotel popular among tourists who came to see the region's famed vineyards was evacuated, according to KGO-TV.

A guest there from North Carolina told the station that she "made a decision to take the rental car through the waist-high water and got two-thirds of the way and then the car stalled".

Image copyright Getty Images

Nina Sheehan said it was a mistake to have tried to pass by vehicle.

Emergency crews always warn people against ever driving through water over 1ft (30cm) deep. Two feet of water can wash away most cars, according to the National Weather Service.

Members of the National Guard were seen towing kayaks, canoes, and jet-skis to the water's edge.

One trapped woman suffered a medical issue and was evacuated by helicopter, the sheriff's office said.

Image copyright Getty Images Image caption Grape fields are underwater in California's wine-producing region

A nearby mudslide, as well as downed trees, is also cutting off road access on Bohemian Highway.

One man, who was trapped with his wife in their vehicle by a mudslide, told KGO-TV that trees were falling all around them as the mud pushed them downhill.

"Oh, they just flew down every which way. They just came running down the hill, these big trees," he said.

Image copyright Getty Images

By Wednesday night the Russian River crested at 45ft - nearly 14ft above flood stage - before beginning to recede.

In nearby Sebastopol, the Laguna de Santa Rosa wetlands rose high enough to swamp the town's main shopping district.

The Russian River Valley is home to more than 300 wineries, according to the Mercury News, and tourists there spent around $2.1bn (£1.6bn) in 2017.

It's not yet clear to what extent the flooding has affected local vineyards, but photos clearly show fields that are underwater.

More rain is forecast in the coming days, weather officials warn, and an increased snowpack in several western states could continue to keep water levels higher than average.