A fast-moving wildfire in California has killed at least one person and destroyed more than 400 homes, with officials describing the rate the fire has spread as "unprecedented".
The so-called Valley Fire in Lake County erupted on Saturday afternoon and spread quickly to a cluster of small communities in the region, forcing the evacuation of thousands of residents.
Officials said an elderly, disabled woman died in the Cobb area, north of San Francisco, that has been especially hard hit by the massive wildfire.
"The resident was apparently unable to self-evacuate and responders were unable to make it to her home before the fire engulfed the structure," the local sheriff's spokesman lieutenant Steve Brooks said.
Evacuated residents recounted chaotic ordeals of having to flee their homes through gauntlets of flame, and some 9,000 structures remained threatened as darkness fell on Monday evening, according to the California Department of Forestry and Fire Protection (Cal Fire).
"That whole place was ablaze. It was like Armageddon," said Steve Johnson, a 37-year-old construction worker from Southern California who was visiting his mother in the fire-ravaged community of Hidden Valley Lake.
"We were literally driving through the flames."
Mr Johnson and his mother safely escaped and spent Sunday night at a high school gymnasium converted into an evacuation centre.
The death marks the first civilian fatality in the wildfires that have devastated the western United States in recent months.
By Monday evening, the blaze had blackened 25,000 hectares of tinder-dry forests, brush and grasslands, and was only about 10 per cent contained, according to Cal Fire.
Fuelled by high winds, the blaze is one of three massive wildfires burning in central and northern California which has been racked by four years of drought.
Four firefighters were hospitalised with second-degree burns in the early hours of the blaze on Saturday.
Cal Fire reported that some 1,000 structures had been lost, at least 400 of them homes.
The property toll is expected to rise as damage-assessment teams reach areas of the fire zone yet to have been surveyed, Cal Fire field battalion chief Mike Smith said.
More than 1,400 firefighters have been assigned to the blaze, he said.
A separate blaze raging since Wednesday in the western Sierras has destroyed 135 homes and 79 outbuildings and was threatening about 6,400 structures, Cal Fire reported.
Together the twin blazes have reportedly destroyed an area nine times the size of Manhattan.
Three other fires are scorching the earth in the neighbouring state of Oregon and 10 further north in Washington state.
While temperatures are cooler than in the past week, conditions remain extremely dry, which allow fires to burn at a rapid rate.
Firefighters from across the country, as well as Australia and New Zealand, have helped tackle the fires. National Guard troops have also been called in.