An estimated 82,000 people have been evacuated as a raging wildfire took hold in San Bernardino County to the east of Los Angeles.
The blaze broke out on Tuesday in a mountain pass and has already engulfed about 15,000 acres of land.
Tens of thousands of homes are at risk from the so-called Bluecut fire. A state of emergency has been declared.
Another fire, the Clayton, which broke out on Saturday in northern California, has destroyed 175 homes.
The Bluecut fire spread with great speed in the parched canyons around San Bernardino. At least a dozen buildings have already been engulfed.
US Forest Service spokeswoman Lyn Sieliet told the BBC: “It is a very fast-moving fire, it has wind behind it.”
California Governor Jerry Brown declared a state of emergency in San Bernardino County to bring in federal assistance.
The blaze forced the closure of a stretch of Interstate 15, the main highway between Las Vegas and Los Angeles area.
Some 700 firefighters are battling to control the blaze in the Cajon Pass.