GLENDORA (CBSLA.com) — Three men were arrested Thursday in connection with a 1,700-acre brush fire in Glendora that destroyed at least five homes and prompted the mandatory evacuation of 3,700 residents.

The Los Angeles County Fire Department and the National Forest Service were battling the fire, which was first reported at 5:40 a.m. in the foothills of the Angeles National Forest.

“At 6:34 am, a Glendora Police Officer detained two subjects running in a flood control wash channel in the 800 block of E. Palm Ave.,” Glendora police said. “U.S. Forestry contacted a third subject in the area of Glendora Mountain Road and Colby Trail around 8:37 am.”

The three suspects, 23-year-old Jonathan Jarrell of Irwindale, 22-year-old Clifford Henry Jr. of Glendora and 21-year-old transient Steven Aguirre, allegedly started a campfire early Thursday morning when the wind picked up and sparked the rapidly spreading Colby Fire. They were booked on suspicion of recklessly starting a fire and were being held in lieu of $500,000 bail.

“Reportedly, they were up , they had set a campfire,” Glendora police Chief Tim Staab said. “They were tossing papers into the campfire and a breeze — reportedly — a breeze had kicked up and set this fire.”

Staab said all three men were “apologetic.”

“They are being cooperative,” Staab said. “I’ve been told by detectives that one has made an admission to our detectives and has admitted to setting this fire.”

Staab said the area where the men were was not a camping area, but people are known to camp in the hills above Glendora.

“They told us they were camping out,” he said. “There’s no evidence to indicate they were living up there.”

About 800 fire personnel and law enforcement, including 16 strike teams, more than 100 engines, eight fixed wing aircraft and seven helicopters, were called in to battle the flames. Cal Fire, Southern California Edison and the California Highway Patrol were assisting with resources. The fire was 30 percent contained as of 10:30 p.m., according to L.A. County Fire officials.

“We’re fighting this fire extremely aggressively both on the ground and in the air,” L.A. County Fire inspector Scott Miller said.