More than a dozen wildfires whipped by powerful winds swept through California wine country have destroying at least 1500 homes and businesses and sending an estimated 20,000 people on a headlong flight to safety through smoke and flames.
One person was killed in a fire further north, in Mendocino County.
The state's fire chief called the damage estimates for the fire 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. Later he said there were likely fatalities.
Mandatory evacuations were ordered after the blazes broke out late Sunday. Long lines formed at gas stations when many families heeded a middle-of-the-night call to get out. A representative of Pacific Gas & Electric said 114,000 customers were without power.
"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 routes, Sonoma County residents struggled to figure out what roads to take.
Many of the fires spread suddenly, whipped by furious winds.
Santa Rosa, the largest city in the fire area with a population of about 175,000, was hit hard. The city lost an unknown number of other businesses and homes as the blaze shut down schools and forced patients at two hospitals to evacuate. A Hilton Hotel was reduced to smouldering ruins.
"Imagine a wind-whipped fire burning at explosive rates. This is 50 miles per hour. Literally it's burning into the city of Santa Rosa ... burning box stores," Pimlott said. "This is traditionally California's worst time for fires."
Napa County Fire Chief Barry Biermann said the fires had burned more than 175 sq km. 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.
Governor Jerry Brown declared a state of emergency in Napa, Sonoma and Yuba counties. Smoke was thick as far away as San Francisco, 100km south of the Sonoma County fire.
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".