A wildfire that began along a popular hiking trail forced 1,000 people to evacuate their homes in the hills northeast of Los Angeles on Sunday, officials said.

An airplane drops flame retardant on a slope Sunday, April 27, 2008, in Sierra Madre, Calif. A wildfire that broke out in a popular hiking area blackened the steep slopes of foothills outside Los Angeles and led to evacuation orders for residents of about 550 homes, authorities said Sunday.

The cause of the nearly 400-acre fire, which started Saturday afternoon as Southern California logged near-record temperatures, was still under investigation, said Elisa Weaver, a spokeswoman for the city of Sierra Madre, California.

Fifty people celebrating a wedding at a mountain campground were lifted from the area by helicopter after the fire cut off their exit trail. No one in the group was harmed.

Temperatures ere expected to climb to 97 degrees Fahrenheit (36 degrees Celsius) on Sunday. Low winds and humidity, however, were expected to help the firefighting effort.

"A lot of that area hasn't burned in 40 years, but the weather has been on our side," Weaver said.

Between 400 and 500 homes were under a mandatory evacuation order, Weaver said, though only one building -- a small storage shed -- had been burned.

The blaze was expected to take up to four or five days to contain fully.

About 400 firefighters were assigned to the fire, which was about 5 percent contained early Sunday morning. Water-dropping airplanes and helicopters were also fighting the blaze.

Sierra Madre is about 20 miles northeast of downtown Los Angeles.

Late last year, strong winds, high temperatures and parched brush after a record drought were blamed for spreading a series of blazes from Santa Barbara to the Mexican border that destroyed thousands of buildings and drove hundreds of thousands of Californians from their homes.

(Chinadaily.com.cn via agencies April 28, 2008)