A combination of 60mph wind gusts and tinder dry brush sent flames roaring towards the centre of the city overnight, leaving another 23,000 people facing possible evacuation on Saturday.

"I never thought I'd use these cliche type words, but last night all hell broke loose," Santa Barbara City Fire Chief Andy Dimizio said.

The rolling green hills of Santa Barbara, studded with the mansions of showbusiness celebrities and their multi-millionaire neighbours, resembled a "war zone" as raging flames and huge plumes of smoke rose into the air.

An ashen grey carpet lay over the normally picturesque landscape, illuminated by dozens of wildfires and clouds of smoke that dwarfed the helicopters dropping water on the blazes.

In the city below, ash rained down like snow flakes. The acrid smell hung thick in the oven-hot air, burning nostrils and causing coughing fits.

Another 3,500 houses and about 100 businesses remained under immediate threat from the fire, which has already consumed 80 homes and turned nearly 9,000 acres of land in the foothills into charred ashes.

No civilian casualties have been reported, although 11 firefighters have been injured. Policemen wearing surgical masks patrolled for looters on quiet streets as defiant residents stared up in shock at the charred mountains.

"We've had fires before but I don't think I've seen it as bad as this," said Paul Willis, 16, a school student. "It's like being in a war zone."

Famous names such as talk show host Oprah Winfrey and British comedian John Cleese have mansions in Santa Barbara and neighbouring Montecito, which are set in a picturesque stretch of California known locally as "the Riviera". Ms Winfrey was understood not to be at her $50 million mansion, but her staff were reported to be making evacuation preparations.

The unpredictable wildfires were particularly dangerous for firefighters drafted to battle the blaze. Three were left with horrific burns when fire overran their vehicle, according to a local official.

Gina Sunseri, a Santa Barbara Fire Department spokeswoman, said: "It's hard to say if we are getting a handle on this because the winds are so unpredictable.

"With winds gusting at 60mph and the temperature around 102 degrees, it's very dangerous out there.

"Also the topography of the mountains is very steep, so the flames can whip down and around very quickly."

Firefighter Mark Metz, still covered in black soot from his last outing and heading back to the hills, was understated when he discussed the danger.

"We do have to get quite close to the fires sometimes, but if things look too bad we back off," he said. "No house is worth losing a life over."

As he spoke, a thick plume of white and gray smoke billowed out of one of the towering peaks of the verdant Santa Ynez mountains. Pushed west by the strong, gusting winds, it spread across the land like a giant cloud, darkening the countryside.

At one point the fire suddenly spread rapidly down the mountain, prompting startled gasps from residents waiting in the town square to hear if they were to be evacuated.

Claudia Barajas, 33, who works at a convenience store, had a look of terror on her face as she watched the fast-moving blaze head in her direction.

She said: "I'm very concerned. You can really see the flames now and the fire is moving so fast. I'm told it is getting very close to some electrical towers at the bottom of the mountain.

"It's particularly worrying for us as we are not really used to this type of thing. We've had a few wild fires in the last year-and-a-half, but before that we had not had one since the 1970s."

Sam Frye, a volunteer for the Montecito Emergency Response and Rescue Action Group, said: "People are obviously worried, with the fire heading in this direction. If the winds would only stop, the fire would die out and we would be fine. But with the way the conditions are now, anything can happen."

On Friday afternoon, sections of the Montecito neighbourhood east of Santa Barbara were being evacuated, including the historic San Ysidro Ranch, where the future President John F Kennedy honeymooned with his wife Jacqueline.