The fire was first reported around 1:45 p.m. near Highway 138 and the entrance to Silverwood Lake. The blaze charred about 20 acres before firefighters were able to make progress on containment.
Evacuations were ordered for the Silverwood Campground, according to the U.S. Forest Service.
The San Bernardino County Fire Department said on Twitter that the blaze may have ignited from a vehicle fire that spread into nearby vegetation.
Highway 138 was closed in both directions between Old Mill Road and Highway 173 due to the firefight.
Firefighters from San Bernardino County, San Bernardino National Forest and CAL FIRE were responding to the blaze.
DEVELOPING...We will add more details to this report as they become available.