Show Low, Ariz. ? A massive wildfire that has destroyed more than 400 homes in the mountains of eastern Arizona was sparked in part by a contract firefighter who hoped to make money fighting the flames, prosecutors said Sunday.

Leonard Gregg, 29, worked part-time as a firefighter for the Bureau of Indian Affairs and was one of the first people called to fight the blaze. According to a statement filed in federal court by a BIA investigator, Gregg said he set the fire so he could get work on a fire crew.

“This fire was started with a profit motive behind it,” U.S. Attorney Paul Charlton said Sunday.

At a hearing in federal court in Flagstaff on Sunday, a tired-looking Gregg said, “I’m sorry for what I did.”

But U.S. Magistrate Stephen Verkamp cut him off, saying he shouldn’t make any admission of guilt at the hearing.

Gregg was arrested Saturday in connection with two fires set June 18 near the Fort Apache Indian Reservation town of Cibeque. One fire was put out, but the other exploded up steep terrain and quickly spread, threatening the town of Show Low and overrunning two smaller communities just to the west.

The wildfire merged with another, started by a lost hiker signaling a helicopter, and became the largest in Arizona history.

By Sunday, the 452,000-acre combined blaze had destroyed at least 423 homes. It was about 35 percent contained by fire lines near Show Low but continued to burn out of control to the west.

According to the criminal complaint, Gregg said he had set the fires near Cibeque by using matches to set dry grass aflame. Before the fire was reported, he told a woman he had to get home because there was going to be fire call, the complaint said.

Gregg didn’t expect the fire to get so big, the complaint said.

If convicted of both counts of willfully setting fire to timber or underbursh, Gregg could face 10 years in prison and be fined $500,000.

Jim Paxon, a fire spokesman, called Sunday’s revelation “gut-wrenching.”

“It causes a lot of angst and heartburn and questioning,” Paxon said.

The judge said an attorney would be appointed for Gregg and set a preliminary hearing for Wednesday. Gregg, a resident of the Fort Apache Indian Reservation, is being held in the Coconino County Jail.

Firefighters continued to fight the blaze Sunday and were focused on keeping the flames from bursting out of steep canyons and into the 600 homes of Forest Lakes, about 40 miles west of Show Low. The fire merged with another blaze, set by a hiker signaling for help, into the largest wildfire in Arizona history.

In Show Low, residents were back in their homes for the first time since June 22.

About 25,000 residents were allowed to return to the area Saturday after firefighters were able to hold the blaze to within a half-mile of Show Low’s edge. The town of 7,700 was untouched, but in nearby communities, dozens of homes had been burned and blacked by the flames.

As residents poured back into the area, they found a patchwork of burned homes around the communities of Pinedale, Pinetop-Lakeside and Hon-Dah.

“I just kept praying and I knew it was going to be all right,” said Mary Capuozzo of Pinetop-Lakeside.

In nearby Linden, residents were still kept from the more heavily damaged subdivision of Timberland Acres, a square mile that had been dotted with log cabins, trailers and ranch-style homes.

Residents of areas farther west of Show Low, including Heber-Overgaard, where more than 200 homes burned, were still under orders to stay out, among 3,500 to 4,000 people still kept from their homes.

In other developments:

• In Wyoming, at least 36,000 acres were ablaze and crews were scrambling to contain six major lightning-caused fires that erupted late last week. Two were in the southeastern part of the state and threatened about seven rural homes; four were in the northeast and threatened about 15 homes.

• Thousands of people fled the South Dakota gambling town of Deadwood because of a wildfire that was 30 percent contained Sunday morning. Two homes and six other buildings were destroyed in the town of 1,380 residents.

• Several grass fires flared up in North Dakota, including a 20,000-acre blaze that burned about 30 buildings and dozens of vehicles in Shields, a town of 15 residents, authorities said.

• Fire crews in Colorado extended their containment lines around a more than 71,000-acre wildfire north of Durango. It was 40 percent contained but still threatened 152 homes. The flames had destroyed 56 houses.