No injuries were reported.
The fire began shortly after 3 p.m. about 10 miles southwest of the Lockwood Valley area. It was about 40 percent contained late Wednesday night and no homes were in its immediate path, said Joe Pasinato, a spokesman for the U.S. Forest Service.
``The fire's looking good, but the low humidity could prove a problem,'' Pasinato said. Humidity was expected to be around 10 percent.
The cause of the fire was under investigation. Investigators initially believed it started in a building and spread to vegetation but later backed off that idea, Pasinato said.
At least three structures were destroyed, one residence and two outbuildings.
More than 400 firefighters from the Forest Service, the California Department of Forestry and Fire Protection and Ventura and Kern counties responded to the blaze.
