Los Angeles  - Fanned by gusting winds, a raging spring wildfire near Santa Barbara, California, grew Friday, prompting the evacuation of 30,000 people as it spread toward the city centre.

Another 20,000 people were placed on evacuation alert as the fire spread across an 8-kilometer front on the mountains above the oceanfront city.

"Literally, last night, all hell broke loose," Santa Barbara Fire Chief Andrew DiMizio said in a press conference. "We saw the fire spread laterally across the top of the city and the fire front extend to almost 5 miles (8 kilometres)."

Spectacular television pictures showed a wall of fire scorching through hillsides and canyons covered in forest, brush and magnificent houses. The blaze had burned 75 homes, many of them luxurious mansions in an area famed for its natural beauty and celebrity residents, including Oprah Winfrey.

About 2,300 firefighters, as well as 246 engines, 10 air tankers and 15 helicopters were battling the blaze, which had grown Friday to more than 1,400 hectares.

The cause remains unknown.

A DC-10 air tanker joined the fight Friday, dropping some 50,000 litres of bright orange fire retardant on the ridge tops in an effort to slow the relentless march of the flames.

The Jesusita fire was ignited Tuesday but exploded out of control Wednesday, fed by the so-called Sundowner winds of up to 80 kilometres an hour. Ever since, the fire has sent clouds of glowing embers and thick blankets of smoke along the coastal mountainsides and toward the densely populated town.

The winds are expected to die down Saturday, giving firefighters a better chance of making a stand against the blaze.

Coming so early in the season, the destructive fire in areas of luxury homes has underscored the growing threat facing California as climate change makes wildfires hotter, bigger and more frequent. The fire came six months after a blaze in the same area burned more than 200 houses. It was the third blaze there in nine months.

California Governor Arnold Schwarzenegger proclaimed a state of emergency Wednesday and toured the site of the fire Thursday. Ten firefighters were injured when the blaze overran their engine.

"This fire has been a great challenge," Schwarzenegger said while viewing the damage. "There's no two ways about it." (dpa)