Three water-dropping helicopters were battling a 10-acre brush fire Friday night in the Castaic area near the 5 Freeway.
Authorities said no homes or businesses were threatened by the blaze, and no injuries were reported.
The fire started close to the intersection of the Old Road and Victoria Road about 8:45 p.m., according to the Los Angeles County Fire Department.
No evacuations have been ordered, officials said.
No cause of the blaze was given, but the extremely hot weather and dry conditions were making it harder for firefighters to get the fire under control quickly.