ANAHEIM, Calif. — A fast-moving brush fire scorched 500 acres of parched hillside and crept into backyards yesterday, forcing authorities to evacuate more than 500 homes, Orange County fire officials said.

At least two homes in Anaheim’s Hidden Canyon neighborhood were on fire and many others were threatened, Anaheim city spokesman John Nicoletti said.

“This is a very dangerous firefight,” said Orange County Fire Authority Chief Ed Fleming. “The terrain is quite rugged, with homes on top of ridges, and the fire picks up speed as it head up the hill.”

No injuries have been reported, Mr. Nicoletti said.

The fire, stoked by hot dry winds and fueled by chaparral, spread south and west quickly in an unincorporated part of Orange County and threatened multimillion dollar homes here and in Anaheim Hills, about 35 miles southeast of Los Angeles. Authorities said the blaze may have been started by a vehicle fire.

Steven Miller, another Orange County Fire Authority spokesman, said winds blowing up to 35 mph were making firefighting difficult for the more than 200 firefighters on the scene.

Temperatures were in the 90s and humidity was at 5%. Firefighters were aided by helicopters and planes dropping water and retardant on the flames, and police went door to door to warn residents to evacuate.

“There is a lot of fire personnel out there and they are doing the best they can, but the weather is not in their favor,” an Orange County Fire Authority spokeswoman, Lynnette Round, said.

The area, like much of Southern California, is under a red flag alert, indicating a high fire danger. A prolonged drought has left the chaparral-covered hills highly combustible.

Robert Canossi, who along with his wife and daughter were evacuated around noon, said he has lived in the area since the 1970s. He waited for news about his home at a nearby elementary school.

“You get used to this, but this is the closest it’s ever come” to so many houses, Mr. Canossi said.