Wildfires whipped by powerful winds have swept through California wine country, destroying at least 1500 homes and businesses and sending thousands fleeing as flames raged unchecked through high-end resorts, grocery stores and tree-lined neighbourhoods.
Officials say at least seven more people have died, bringing the total number of fatalities to 10.
The Sonoma County Sheriff's Office tweeted Monday that seven fire-related deaths were reported from fires there.
California fire officials reported earlier that two people died in Napa County and one died in Mendocino County.
The flames were burning "at explosive rates" because of 50mph winds, said Ken Pimlott, director of the California Department of Forestry and Fire Protection.
Fourteen large fires were burning, spread over a 200-mile region north of San Francisco from Napa in the south to Redding in the north.
CalFire said several counties were struggling to contain a total of 14 major fires burning out of control.
The state's fire chief called the damage estimates conservative and said the fires were burning throughout an eight-county swath of Northern California, including Napa, Sonoma and Yuba counties.
Numerous people had been hurt and some were missing, although no estimates were immediately available, said California Department of Forestry and Fire Protection Director Ken Pimlott.
Mandatory evacuations were ordered after the blazes broke out. Long lines formed at gas stations when many families heeded a middle-of-the-night call to get out.
"It was an inferno like you've never seen before," said Marian Williams, who caravanned with neighbours before dawn as one of the wildfires reached the vineyards and ridges at her small Sonoma County town of Kenwood.
Williams could feel the heat of her fire through the car as she fled.
"Trees were on fire like torches," she said.
With downed trees or flames blocking some routes, Sonoma County residents struggled to figure out what roads to take.
Fires also burned just to the east in the Napa County as well as in Yuba, Butte and Nevada counties - all north of the state capital. The firefighting agency Cal Fire tweeted that as many as 8,000 homes were threatened in Nevada County, which lies on the western slope of the Sierra Nevada.
Napa County Fire Chief Barry Biermann said the fires had burned more than 68 square miles (176 sq. kilometres). Crews had not yet been able to contain a fire heading toward downtown Napa.
"Right now, with these conditions, we can't get ahead of this fire and do anything about the forward progress," Biermann said. He said there were seven large fires burning in Lake, Sonoma and Napa counties.
Governor Jerry Brown declared a state of emergency in Napa, Sonoma and Yuba counties.
Smoke was thick in San Francisco, 60 miles (96 kilometres) south of the Sonoma County fire.
John Dean was driving to his Sonoma County home early Monday when he saw a house on fire along the road. Soon he saw more houses engulfed in flames.
"I mean blazing, falling down on fire," he said.
Dean sped to his home in Kenwood, alerted neighbours and fled to the town of Sonoma. He was one of hundreds of evacuees who streamed into a 24-hour Safeway market overnight, while authorities set up an official evacuation center.
Maureen McGowan was house-sitting for a brother near Kenwood, and said both of the homes on his property were on fire when she left. At the Safeway, she pointed to her feet, still in slippers. She had fled so fast that she hadn't put on her shoes.
Officials did not yet have a count on how many properties were affected, either by the fire directly or by evacuations, said Belia Ramos, chairwoman of the Napa County Board of Supervisors.
"We're focusing on making evacuations and trying to keep people safe. We are not prepared to start counting," she said shortly after sunrise.
The "tremendous" wind gusts were making the fire unpredictable, she said. "It's something that we're having to be very cautious about."
Ann Dubay, a spokeswoman for the Sonoma County Emergency Operations Center, said the area where the largest fire started was relatively rural but the flames "went through many, many neighbourhoods," and authorities did not know how many structures were gone.
Emergency lines were inundated with callers reporting smoke, prompting officials to ask that the public "only use 911 if they see actual unattended flames, or are having another emergency."
Business owner Andy Lahiji stood before a burned-out warehouse where he said he had lost his inventory of furniture and other property. He said it took firetrucks ages to arrive.
"They said, 'We have so many other places to go, you have to wait.' And then when they came, they had only a couple of guys," he told the station. "I feel very sad. I'm glad nobody got hurt. Hopefully insurance takes care of it."
The National Weather Service said widespread wind gusts between 35 mph and 50 mph were observed in the north San Francisco Bay region and isolated spots hit 70 mph. The winds were expected to subside at midday.
Community centers, the Sonoma County Fairgrounds and other local centers were opened for evacuees.