A 300-acre blaze was burning through steep forestland in the San Jacinto Mountains west of Palm Springs on Saturday, but no homes were threatened.
The fire broke out in the mountains just south of Banning, a town of 30,000 in the pass that connects Riverside and Palm Springs through Interstate 10.
Mark Annas, a spokesman for the California Department of Forestry and Fire Protection, said the Riverside County blaze broke out at 11:43 a.m. and 400 firefighters were on the scene by midafternoon. The fire was near California 243, about two miles south of Banning.
Winds were reported at 15 to 20 miles per hour, and the temperature was 80 degrees, with a relative humidity of 8%.