The fire started close to Fontana east of Los Angeles and winds in excess of 30 mph pushed it west into the mountains and canyons of Rancho Cucamonga, county fire spokeswoman Angie Samayoa said.
The fire was 60 percent contained by midmorning.
People in about 100 homes near a Buddhist temple were told they may want to evacuate but were not ordered to do so, Samayoa said.
"Homes are not directly in the line of fire," Samayoa said.
About 350 firefighters were on the scene and aircraft dropped water on the flames, Samayoa said.
"It sounds like they're holding it ... it doesn't seem to be progressing so far," she said.
There were no reports of any smoke or fire near freeways and no word of any injuries, officials said.