A wildfire fed by parched land and high winds spread in southern California on Saturday, forcing hundreds of people to leave their homes as the blaze formed destructive columns of flames known as fire tornadoes.
The so-called Sherpa Fire in Santa Barbara County, about 145km northwest of Los Angeles, had burned through about 3,161 hectares by Saturday evening, officials said.
Firefighters estimated the fire was 45 per cent contained after early evening "sundowner winds" that can whip through the area's coastal canyons did not emerge overnight on Friday.
"We had a very good night last night ... We've had no life loss, no major injuries and no major structural loss," Santa Barbara County Fire Chief Eric Peterson told a news conference.
But county officials issued a new "red flag warning" for gusty winds from Sunday to Tuesday.
More than 1,200 firefighters have been dispatched to battle the flames, fueled by dry chaparral and grass in coastal canyons about 32km northwest of the affluent city of Santa Barbara.
"Now is the time to gather your family members, pets and important documents in case you need to leave quickly," the Santa Barbara Sheriff's Office warned people living in areas threatened by the fire.
The fire broke out on Wednesday and has been expanding since then, forcing mandatory evacuations in some areas and putting others under evacuation warnings.
The fire is one of a series of blazes in western and southwestern states brought about by high temperatures and a prolonged dry spell. One of the largest has been southeast of Albuquerque, New Mexico, that has destroyed about two dozen homes and forced evacuations.
More than 700 personnel were fighting the so-called Dog Head Fire that has burned through about 7,129 hectares of timber and logging zones in four days. Firefighters said it was 9 per cent contained as of Saturday evening. Governor Susana Martinez this week declared a state of emergency to free up resources to fight the blaze.
For an area stretching from southern California to southern Nevada and into Arizona, the National Weather service has put out "red flag warnings," indicating conditions that could lead to dangerous fires.
It has also issued a heat advisory for large parts of New Mexico, Texas and Oklahoma.