More than a dozen wildfires whipped by powerful winds have swept through California wine country, destroying at least 1,500 homes and businesses and sending about 20,000 people fleeing for safety.
The state's fire chief called the damage estimates conservative and said the fires were burning throughout an eight-county stretch of northern California, including Napa, Sonoma and Yuba.
Numerous people had been hurt and some are missing, although no estimates were available, said California Department of Forestry and Fire Protection director Ken Pimlott.
Mandatory evacuations were ordered after the blazes broke out late on Sunday. Long queues formed at filling 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 as one of the wildfires reached the vineyards and ridges at her small Sonoma County town of Kenwood.
With downed trees or flames blocking some routes, Sonoma 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 there were no reports of injuries or deaths, although the fires had burned more than 68 square miles. Crews had not yet been able to contain a fire heading towards central Napa.
"Right now, with these conditions, we can't get ahead of this fire and do anything about the forward progress," Mr Biermann said, adding 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 south of the Sonoma County fire.
Ann Dubay, a spokeswoman for the Sonoma County Emergency Operations Centre, 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".
The National Weather Service said widespread wind gusts between 35mph and 50mph were observed in the north San Francisco Bay region and isolated spots hit 70mph. The winds were expected to subside later.
Community centres, the Sonoma County Fairgrounds and other local centres were opened for evacuees.
AP