A wildfire destroyed hundreds of homes and forced thousands of residents to flee as it roared unchecked through the northern California village of Middletown and several nearby communities, fire officials said on Sunday.
The so-called Valley Fire, now ranked as the most destructive among scores of blazes that have ravaged the U.S. west this summer, came amid what California fire officials described as "unheard of fire behaviour" this season.
A separate fire raging since Wednesday in the western Sierras has levelled more than 130 buildings and was threatening about 6,400 other structures, the California Department of Forestry and Fire Protection (Cal Fire) reported.
Governor Jerry Brown declared a state of emergency in both areas, and mandatory evacuations were expanded as shifting winds sent flames and ash from the Valley Fire toward a cluster of towns in the hills north of Napa Valley wine country.
Reuters video footage from Middletown showed a smoking, devastated landscape of blackened, burned-out vehicles and the charred foundations of buildings that had been reduced to ash.
"While crews have not had a chance to do a full damage assessment ... we know 100s of structures have been destroyed," Cal Fire spokesman Daniel Berlant said in a Twitter post.
Property losses included "countless homes and other buildings," he added in a subsequent video news briefing.
The Valley Fire has consumed more than 50,000 acres since igniting Saturday in rural Lake County, California, about 50 miles west of Sacramento, the State capital, fire officials said on Sunday.
