By Jill Serjeant

LOS ANGELES, Oct 26 (Reuters) - A brush fire blamed on arsonists swept through the desert hills near Palm Springs on Thursday, killing four firefighters, sending residents fleeing and trapping hundreds more in a rural park for recreational vehicles.

Whipped by warm winds after a long, dry summer, the fire roared out of control through about 24,000 acres (9,700 hectares) in less than 24 hours, destroying at least 10 homes and engulfing a firetruck, fire officials said.

By nightfall, the fire line stretched 15 miles (24 km) along canyons and rugged hills 90 miles (145 km) east of Los Angeles and 17 miles (27 km) northwest of Palm Springs.

But Riverside County Fire Department Chief John Hawkins said the more than 1,000 firefighters were finally making progress. "We are doing better with it. We are saying 5 per cent containment. That might not sound like a lot but it really, truly is," Hawkins said.

He said crews would work through the night despite strong winds and acrid billowing clouds of smoke. "We are going to hit it hard," he told a news conference.

Hawkins said the fire was caused by arson and that the deaths of the firefighters were being treated as homicide. "A deliberately set fire that leads to the death of anyone constitutes murder," he said angrily.

A reward of $100,000 was offered to catch the arsonists and Riverside County officials said they had received several tips that were being followed up.

About 700 people were ordered to leave their homes as the blaze took hold.

Many were forced to flee at a moment's notice, leaving belongings and pets behind.

FLAMES '100 FEET TALL'

"The flames were 100 feet (30 metres) tall, burning on both sides of the road. I didn't think I would make it," said Charles Miner, who suffered slight burns to his hand.

Hawkins said an additional 400 to 1,000 people were trapped in a recreational vehicle park in the hills because firefighters had been unable to get them out.

"They are sheltered in place, which means we could not evacuate them in time. They're going to encounter heat and smoke but they are probably going to be OK. We have firefighters with those people," he said.

Officials were unable to give precise figures for the numbers of homes destroyed or those injured because of the thick smoke and remote area.

One man said he watched his home burn. "My neighbor's house, everything around me (burned). My son got burned driving out," the man, who identified himself as Victor, told Fox11 TV.

Many left behind dogs, cats and horses.

"We didn't have time to get our animals. We have five Dobies and they've just had eight puppies. And then we have a bunch of cats," a distraught Desiree Atkins told reporters.

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