AP Photo/Nick Ut LOS ANGELES (Reuters) - A fast-moving California wildfire, started accidentally by three campers, roared out of control in foothills above Los Angeles on Thursday, destroying five homes and forcing some 3,600 residents to flee, fire and law enforcement officials said.

The wind-whipped blaze began before dawn in the Angeles National Forest north of Glendora, about 40 miles east of downtown Los Angeles in the foothills of the San Gabriel Mountains.

By mid-morning, the so-called Colby Fire had blackened more than 1,700 acres of drought-parched brush and vegetation, Los Angeles County fire officials said. A thick pall of black smoke hung over eastern Los Angeles County, stretching west over the Pacific Ocean.

But as winds diminished and temperatures cooled later in the day some 700 firefighters, aided by eight fixed-wing aircraft and seven helicopters, were able to keep the flames from advancing any further.

As darkness fell over Southern California authorities said the blaze was 30 percent contained and many of the evacuees were allowed to return home.

Three men who were spotted leaving the area where the blaze began were taken into custody, Glendora Police Chief Tim Staab said. Each was arrested on suspicion of recklessly starting a fire and was being held on $20,000 bail, he said.

"Reportedly they set a campfire and were tossing papers into the campfire and a breeze kicked up and set the fire," Staab said. "They are being cooperative. I'm told one has made an admission to our detectives and has admitted setting this fire."

The suspects were identified as Clifford Eugene Henry Jr. 22, of Glendora; Jonathan Carl Jarrell, 23, of Irwindale; and Steven Robert Aguirre, 21, of Los Angeles. Staab said Aguirre was homeless but that the men were not living at the campsite.

HISTORIC MANSION SAVED

The flames prompted residents in parts of Glendora and neighboring Azusa to leave their homes on the order of authorities. Temporary shelters were set up at an American Legion hall, a community center and a high school.

The fire burned five homes to the ground and damaged 17 other structures, Los Angeles County Fire Chief John Tripp said at a late afternoon press conference. Three people, two of them firefighters, suffered minor injuries.

About 3,600 people had been forced from their homes, with about 1,600 allowed to return, U.S. Forest Service said. Some 3,000 homes had been evacuated.

Los Angeles County Fire Department Inspector Tony Akins said that between 1,700 and 2,000 residents remained away from home as of late Thursday evening.

"We have reached the summit of evacuations and the numbers are slowly decreasing," with some Glendora residents being allowed to return, Akins said.

The hot, dry Santa Ana winds would likely peak between 2 a.m. and 10 a.m. on Friday morning, making work harder for firefighters toiling overnight and raising concerns the fire would burn further into the national forest, Akins said.

Authorities said crews fought to save the Singer Mansion, a local landmark designed in the 1920s by architect Wallace Neff, but that a guest home and garage on the property were damaged.

Several elementary and middle schools and at least one high school were shut for the day, along with Citrus College, located about 2 miles from the fire lines, and Glendora city manager Chris Jeffers said the city had declared a state of emergency to free up resources.

The South Coast Air Quality Management district issued a smoke advisory for Los Angeles County and nearby communities, urging people in affected areas to remain indoors with doors and windows closed.

As the day wore on the Santa Ana winds that had whipped the flames had died down, giving firefighters a chance to gain a measure of control over the blaze, officials said.

"Early this morning, when it broke out, it burned really rapidly, and it does appear like it's laying down right now,"Los Angeles County Fire Department spokesman Keith Mora said. "We're just trying to gain control prior to the heat-up in the afternoon."

The fire was burning in steep terrain, near where houses were built right up to the foot of the San Gabriel Mountains, and some isolated homes were nestled in the brush at the location of the blaze, Mora said.

"The topography is just really dangerous," he said. Officials said the foothills above Glendora had not seen a major wildfire since 1968.

With Southern California suffering through several years of drought, officials had predicted a particularly intense fire season. Red-flag warnings, indicating critical conditions, had been posted for many areas.

(Reporting by Dan Whitcomb and Alex Dobuzinskis in Los Angeles; Additional reporting by Eric M. Johnson in Seattle; Writing by Dan Whitcomb; Editing by Cynthia Johnston, Bernadette Baum, Leslie Adler, David Gregorio and Cynthia Osterman)