The blaze, which broke out in a motor home on Sunday afternoon, was 90 percent contained Monday morning, said Stephanie Swanstrom, a county fire information spokeswoman.
It had threatened as many as 400 homes before firefighters began to surround it overnight. The fire, which spread from the motor home to nearby vegetation, destroyed two mobile homes and nine vehicles.
About 540 firefighters, aided by four helicopters and two air tankers battled the flames throughout the day Sunday until the aircraft had to be grounded at dusk.
Temperatures, which reached the 90s in the area on Sunday, were expected to soar to near 100 on Monday.
Meanwhile, fire investigators were trying to determine the cause of the motor home blaze.
``Apparently it overheated and then caught fire,'' said Harriet Costo, 74, who watched the blaze from a nearby hill.
The area is about 100 miles east-southeast of downtown Los Angeles.
The wildfire was the largest in Southern California so far this year. Six months ago, the region was ravaged by a series of firestorms that killed 24 people, destroyed more than 3,600 homes and burned nearly 740,000 acres.
