The so-called Water Fire started just after 8:30 a.m. right off the 5 Freeway. The fire charred approximately 550 acres by 5 p.m. and was 50 percent contained.
The Kern County Fire Department says crews have made progress on the blaze; however, 45 structures remain threatened. Approximately 300 firefighters are on scene.
Residents in the Digier Canyon area have been relocated to El Tejon School, according to fire officials, but evacuation orders are expected to be lifted Tuesday night.
Authorities say the fire burned quickly due to large areas of grass and steep terrain.
One lane of the southbound 5 Freeway was affected by the fire, which was burning between Lebec and the Grapevine.
The cause of the blaze was unknown.