Firefighters were battling a 3-acre brush fire Thursday evening at a nature preserve in Claremont.
The fire was reported about 5:45 p.m. in the 1500 block of North College Avenue, said Robert Diaz, a supervising dispatcher with the Los Angeles County Fire Department.
More than two hours later, firefighters were still trying to control the blaze. No injuries were reported, and no structures were threatened, Diaz said.
The fire was at the Robert J. Bernard Biological Field Station, a wooded preserve within the campus of the Claremont Colleges.
The nearby Rancho Santa Ana Botanic Garden, which is dedicated to California's native plants, did not appear to be affected by the fire.
It's unclear what sparked the blaze.