A brush fire was burning in thick brush in the hills south of Chino on Tuesday but had not forced any evacuations, officials said.
The flames grew to cover 120 acres after breaking out near Highway 71, south of Euclid Avenue, around 2:20 p.m., according to Cal Fire Riverside.
It was being dubbed the Euclid Fire.
The blaze was 15 percent contained by 10:30 p.m. It had not yet presented a threat to any structures.
But smoke from the fire was still a problem for residents, and had spread as far as Perris, fire officials said. The 71 Freeway had also been shut down for a time, but was later reopened.
Video obtained by KTLA showed a car on fire in the area that could have sparked the blaze, but authorities had not confirmed what led it to break out.
The 120 firefighters at the scene were from several agencies, including the Corona, Riverside and Ontario fire departments and Chino Valley Fire District. One crew member was being evaluated for an injury that was not life-threatening, Cal Fire said, without providing further details.
The flames were also being attacked with helicopters.
Fire officials did not say in which direction the blaze was spreading. No further details were immediately available.