The fire was reported about 8 a.m. near Sierra Highway. By afternoon it had grown to 600 acres, but firefighters from the Forest Service, Los Angeles County and Cal Fire had it 50 percent contained.
Twenty-six aircraft helped fight the blaze, including two Super Scoopers. Officials said 300 firefighters were at the scene.
"You have one small road that runs to the bottom of this drainage, everything else we're flying folks in and we're using aircraft to fight this fire. We have dozers out there that are punching the line in trying to stop this fire," said Nathan Judy of the Forest Service.
No homes or structures were threatened.
A command post was established at Sierra Highway and Mint Canyon Road.
Full containment was expected by 6 p.m. Sunday.
The Associated Press contributed to this report.