The fire moved back on itself Monday as the Utah National Guard acknowledged it wasn't the first time that live-fire exercises had sparked a fire at Camp Williams, a sprawling compound 30 miles south of Salt Lake City.
"There's always the possibility that some ammunition will catch brush on fire. We felt like we had it extinguished yesterday, then some embers reignited in the wind and it got away from us," Lt. Col. Hank McIntire told The Associated Press on Monday. "That's when the wind picked up and got it going again, and it rolled through Camp Williams."
Residents and Salt Lake County Mayor Peter Corroon were questioning the National Guard's decision to fire weapons in dry and windy conditions, but McIntire said wind wasn't a factor until after the fire took hold.
"It can create some issues, and I know people are frustrated. We're working hard to make sure we know what happened," Corroon told KUTV-TV in Salt Lake City. "It's a good question to ask and investigators are finding out why it happened."
The roughly 10,000-acre fire moved in on the small community of Herriman late Sunday, said Captain Brad Taylor.
By early Monday, 1,652 homes had been evacuated, said fire information officer Jason Curry. Four houses were lost, said Steve Sautter, manager of Salt Lake County's joint information center. Many others were threatened until winds shifted overnight.
"The fire is blowing back on itself," Sautter said Monday.
A shelter for evacuees without lodging was set up at a local high school.
Herriman is rural community on the southwest side of the Salt Lake Valley. It's flanked to the south and west by mountains. North and west are the valley's suburban communities, with a combined population of about a million.
McIntire told the AP that dry brush had caught fire during artillery training on a machine gun range, and soldiers did not have the manpower or equipment to stop it from rapidly spreading.
"It was kind of a perfect storm scenario where once the fire started on the firing range at the National Guard base, the wind really kicked up," said Lt. Don Hutson of the Unified Police Dept., the agency that oversees Salt Lake County. "Literally, the fire was coming down into the backyards of many of these residents."
All that remained at one of the destroyed log homes was a burned out chimney standing near an empty animal pen where the owners, desperate to flee in approaching fire, set two horses and a sheep free and hoped the animals could get themselves out of danger.
The fire had caused no major injuries, officials said, although two police officers were treated for smoke inhalation and a third for minor injuries after being hit by the vehicle of a driver trying to return home, the Deseret News reported.
Resident Melissa Kula told the Tribune that she and her husband packed their car, then left their home just as flames were nearing their property. "I'm devastated, to say the least," she said.
Winds racing through the area at 40 to 50 miles per hour pushed the fire over a mountain ridge and into the Salt Lake Valley, Hutson said.
"It was lifesaving efforts trying to get people out of the area because of a very, very fast-moving fire - literally moving faster than anybody could run," he said.
To help battle fire, the Guard enlisted 124 troops and three Blackhawk helicopters, officials said. Corroon issued an emergency declaration at 11:30 p.m., and the Federal Emergency Management said it would pay 75 percent of the state's firefighting costs.
Several hours after the fire sparked, crews with the Unified Fire Authority crews were enlisted to help battle the blaze. The first round of mandatory evacuations, which included 262 homes, was ordered at 7 p.m., Taylor said. Later, an additional 1,000 homes were ordered evacuated, he said.
All Salt Lake County residents were asked not to use their cell phones to keep lines open for emergency communication, and volunteers evacuated animals from the area.
"We can see the flames at the top of the hill," Faith Ching, owner of Ching Animal Farm and Rescue, told the Deseret News just before the fire reached some of the houses. "I don't want to take a chance. It's really scary."
Associated Press writers Paul Foy in Salt Lake City and Sofia Mannos in Washington, D.C., contributed to this report.