Wildfires fanned by strong winds have swept through northern California's wine country, killing at least 10 people, destroying hundreds of homes and businesses and forcing some 20,000 people to flee.
The deaths brought the official wildfire-related toll in California this year to 13, the greatest loss of civilian life from a single cluster of blazes in the state in a decade, state fire officials said on Monday (local time).
Governor Jerry Brown declared a state of emergency for Napa, Sonoma and Yuba counties, encompassing some of the state's prime wine-making areas, as the blazes raged unchecked and engulfed the region in thick, billowing smoke that drifted south into the San Francisco Bay area.
He later extended the declaration to include four more northern California counties and Orange County in Southern California, and requested a US presidential disaster declaration to support state and local firefighting resources.
Sonoma County bore the brunt of the fatalities, with seven fire-related deaths confirmed there, according to the sheriff's department.
Two died in Napa County and one in Mendocino County, according to the California Department of Forestry and Fire Protection (CalFire).
Details of those deaths were not immediately available from state or local officials.
But KGO-TV in San Francisco, citing unnamed California Highway Patrol sources, described one victim as a blind, elderly woman found in the driveway of her home in Santa Rosa, a town in Sonoma County.
The death toll could climb higher, said Brad Alexander, a spokesman for the governor's Office of Emergency Services. More than 100 people were treated for fire-related injuries such as burns and smoke inhalation, CNN reported.
The toll marks a 10-year record for civilian wildfire fatalities in the state, dating back to 14 who lost their lives in a series of blazes that swept San Diego County and other parts of Southern California in October 2007, according to CalFire spokeswoman Janet Upton.
On Monday, thousands of firefighters battled wind gusts in excess of 80 km/h that have rapidly spread 15 separate wildfires across some 30,000 hectares in northern California since erupting late on Sunday night, according to CalFire spokesman Daniel Berlant.
About 1500 homes and commercial buildings have been destroyed throughout the region, Ken Pimlott, director of CalFire, told reporters.
Two hospitals were forced to evacuate in Sonoma County, state officials said.
A separate wildfire on Monday torched at least a half-dozen homes in the affluent Anaheim Hills neighbourhood of Southern California's Orange County, forcing the evacuation of hundreds of residents, authorities said.
That blaze erupted along a freeway off-ramp and spread quickly in gusty winds to scorch some 2000 hectares in a matter of hours, fire officials said.
Still, the situation there paled in comparison to one of the fiercer blazes in northern California, the so-called Tubbs fire, which charred about 11,000 hectares in Napa and Sonoma counties, an area world-famous for its vineyards.
San Francisco authorities issued an air quality alert due to smoke from the fires, which residents said they could smell since early morning.