Firefighters killed as out-of-control blaze devastates California

A fast-growing California wildfire has killed two firefighters and prompted 38,000 evacuations, destroying scores of homes and threatening other dwellings and businesses.

Firefighters and police "went into life-safety mode," hustling door to door to usher civilians out of harm's way, said Scott McLean, a spokesman for the California Department of Forestry and Fire Protection (CalFire).

The Californian National Guard has send 800 soldiers and airmen to help the fight.

Streets in the badly affected town of Redding were all but deserted, with thick, sickly-brown smoke filling the air.

Gale-force winds last night created a fire "tornado" said CalFire Director Ken Pimlott.

"This fire was whipped up into a whirlwind of activity, uprooting trees, moving vehicles, moving parts of roadways," Pimlott said.

"These are extreme conditions, this is how fires are in California," he said. "We need to take heed and evacuate, evacuate, evacuate."

Governor Jerry Brown requested emergency federal assistance to prevent an "imminent catastrophe" as local officials tried to find supplies and water for the tens of thousands of evacuated residents and care for horses and cattle rescued from ranches and farms.

CalFire reported 65 structures destroyed by the blaze, but McLean called that tally a "placeholder" figure that would grow significantly, with the number of homes lost likely to run into "the hundreds."

The fire scorched 18,000 hectares by Friday and was just three per cent contained as ground crews, helicopters and airplanes battled the flames for a fifth day.

High temperatures and low humidity were expected for the next seven to ten days, said Pimlott.

"This fire is a long way from done," he said.

The blaze in Redding yesterday killed a bulldozer operator working with fire teams to clear brush around the fire.

A member of the Redding Fire Department was also reported killed on today.

A Redding hospital said it had treated eight people, including three firefighters.

Local Rob Wright, 61, and his wife stayed to fight off flames with a high-powered water hose.

"We were fortunate enough that the wind changed hours ago, and it is pushing the fire back," said Wright.

"We are just waiting it out ... crossing our fingers and hoping for the best."

The devastation in California comes less than a week after a powerful blaze tore through large parts of Athens, Greece. At least 86 people have been killed and countless others are missing with rescue divers searching the surrounding ocean waters for bodies.

Authorities believe the fire in Athens was deliberately lit.

With AAP.