The fire three hours north of Los Angeles -- dubbed the Erskine fire -- had spread to an estimated 5,000 acres, prompting the mobilization of hundreds of firefighters, the news website Inciweb said.
The authorities closed several highways and evacuated two schools and a retirement home in the agricultural and oil region after the blaze started yesterday afternoon due to unknown causes.
The blaze is "extremely dangerous, extremely volatile," Kern County Fire Captain Tyler Townsend told the Los Angeles Times. "It's one of the most devastating I've ever seen."
Temperatures that climbed to more than 40 degrees Celsius earlier this week increased the risk of fire.
More than fourteen large fires are currently raging in the United States, mostly in the southwest, where a record heat wave left at least five dead earlier this week.