The blaze roared through dry brush and trees in the foothills of Kern County, central California, late Friday, destroying dozens of homes and forcing thousands of people to flee.

An official said some 800 firefighters were battling the out-of-control wildfire, with several hundred more on their way to lend support.

The fast-moving fire broke out in the Lake Isabella area, about a three hours' drive north of Los Angeles, late on Thursday. By Friday afternoon, it had spread across 30,000 acres (121 square kilometers).

Authorities closed several highways and warned the more than 3,000 residents of the community of Lake Isabella to be prepared to evacuate.

Kern County Sheriff Donny Youngblood said an elderly couple trying to flee the flames were overcome with smoke and killed near their home. The sheriff added that crews would be sent in to search burnt out properties for further victims.

Scorching heat, warm winds and drought-hit terrain have caused several huge wildfires across the state in the past week.

"The forces of nature collided with a spark," Kern County Fire Chief Brian Marshall said, adding that crews faced a "firefight of epic proportions" as they tried to protect neighborhoods. Three firefighters were taken to hospital suffering smoke inhalation.

California Governor Jerry Brown has declared a state of emergency, freeing up money and resources to fight the blaze.

nm/jlw (Reuters, AP, AFP)