More than 180,000 people have been forced to flee their homes after "historic" winds whipped up a wildfire in northern California 's wine country and forced the state's largest utility company to cut electricity for millions to prevent more fires.

It's one of the biggest evacuations in Sonoma County's history, and California governor Gavin Newsom has now declared a state of emergency across the state, saying: "We're deploying every resource available as we continue to respond to these fires and unprecedented high-winds."

The current wildfire, called the Kincade fire, started on Wednesday night and is only 10 per cent contained, the California Department of Forestry and Fire Protection said on Sunday. Authorities expanded evacuation orders over the weekend, clearing out parts of Santa Rosa, which was devastated by a wildfire two years ago.

The blaze grew by almost 4,000 acres overnight into Sunday to 30,000 acres (47 square miles) and has destroyed almost 80 buildings.

Powerful winds and gusts of up to 90mph on Sunday are making the fire even more difficult to deal with, leading to "erratic fire behaviour" and sending embers travelling for miles, authorities warned.

The National Weather Service sad the fire was "potentially a historic event given the strength and duration of the winds".

Utility firm Pacific Gas and Electric Company (PG&E) has been shutting down parts of the power network over fears that gusts could knock down power lines and trigger more fires. It has left 2.3 million people across 38 counties without power.

The Sonoma County sheriff pleaded with residents in the evacuation zone to get out immediately, citing the 24 lives lost when a wildfire swept through the region two years ago.

"I'm seeing people reporting that they're going to stay and fight this fire," Mark Essick said. "You cannot fight this. Please evacuate."

The Healdsburg area lost one of its historic attractions to the flames Sunday when embers carried by the winds sparked a blaze that engulfed the Soda Rock Winery whose buildings included a general store and post office founded in 1869. The winery was about 10 miles outside the town of Healdsburg.

Evacuations also hit inmates at the North County Detention Facility in Santa Rosa and about 100 Sutter Santa Rosa Regional Hospital patients.

What sparked the current fires is unknown, but PG&E said a 230,000-volt transmission line near Geyserville malfunctioned minutes before that blaze erupted on Wednesday night.

The possible link between the wine country fire and a PG&E transmission line contained grim parallels to last year when most of the town of Paradise burned, killing 85 people in the deadliest US blaze in a century. State officials concluded a PG&E transmission line sparked that fire.

Another fire north of Los Angeles is now 55 per cent contained after it destroyed 18 structures. Nearly all the 50,000 Santa Clarita residents ordered to evacuate are now allowed back home after Santa Ana winds began to ease.

Marcos Briano returned to his neighbourhood on Saturday to find destroyed homes on his street. The 71-year-old said: "I'm thankful that nothing happened to my house, but I feel bad for my neighbours."

Sheriff's officials said human remains were found within the wide burn area, but it is unclear if the death is connected to the blaze.

Agencies contributed to this report
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