The blaze was reported at 9:01 p.m. By 11 p.m., the wind-whipped fire had consumed about 250 acres of grass and brush surrounded by homes on all sides below, according to Capt. Mark Savage of the Los Angeles County Fire Department.
Structures in the area, including ranches, were being protected, Savage said. Evacuations were not anticipated. One ranch evacuated voluntarily.
About 250 firefighters were battling the blaze, which was being spread by winds of 20 mph.
Lake Elizabeth Road from 25th Street West to Godde Hill Road was closed, as were parts of Tierra Subida Avenue north of West Avenue S.
The cause of the fire was not known.