Parts of California's wine region are being ravaged by fast-spreading fires that have killed at least 10 people.
Mass evacuations have taken place and at least 1,500 properties have been destroyed. Seven people were killed in Sonoma county, authorities said.
About 20,000 people fled from Napa, Sonoma and Yuba counties after some of the state's worst-ever wildfires broke out.
The governor of California has declared an emergency.
"These fires have destroyed structures and continue to threaten thousands of homes, necessitating the evacuation of thousands of residents," the declaration said.
Along with the deaths in Sonoma county, two people were killed in Napa county and one in Mendocino county when thousands of acres burned in one valley.
Further injuries have been reported and some people are said to be missing.
Marian Williams of Kenwood, Sonoma county, said she and her neighbours had fled the flames in a convoy of vehicles.
"It was an inferno like you've never seen before," she told broadcaster NBC.
The head of California's Department of Forestry and Fire Protection, Kim Pimlott, said that about 1,500 buildings had already been destroyed.
It is not yet known how the fires started on Sunday night.
Napa county's fire chief warned that conditions were hindering firefighting efforts, as further resources were brought in from across the state.
Dozens of vineyard workers were reportedly airlifted to safety overnight.
The fires are particularly fast-spreading because of the combination of high winds, low humidity and hot, dry weather.
The National Weather Service has issued a warning for the San Francisco area that "any fires that develop will likely spread rapidly".
One vineyard owner told the LA Times that he thought his property was likely destroyed after he and his family escaped from a fire late on Sunday night.
"There was no wind, then there would be a rush of wind and it would stop. Then there would be another gust from a different direction. The flames wrapped around us," Ken Moholt-Siebert said.
"I was just being pelted with all this smoke and embers.
"It was just really fast."
The California fire service estimates that more than 70,000 acres have already been destroyed in at least 14 fires, making it one of the most destructive outbreaks California has seen.