Firefighters were battling a brush fire Tuesday afternoon near the 5 Freeway north of Castaic that had burned about five acres.
Three helicopters were dropping water on the blaze, which was burning near Templin Highway, the Los Angeles County Fire Department said.
On the ground, camp crews and fire engines were trying to stop the forward progress of the blaze. No structures were threatened, the department said.
Commanders at the scene reported winds from the south at 6 mph to 11 mph.
The department had requested that at least one lane of the busy freeway be shut down for personnel and equipment, according to the California Highway Patrol.
[Updated 5:03 p.m.: Two northbound lanes of the freeway have been closed, the CHP said.]