HAMILTON, Mont. – A wildfire roaring through the Bitterroot National Forest in Western Montana has destroyed at least 14 homes.

Ravalli County Sheriff Chris Hoffman said Monday night that his office is still trying to contact all of the affected homeowners, and evacuations remain in place because of the active fire.

The fire that started Sunday afternoon about 5 miles southwest of Hamilton led county authorities to order residents of about 500 homes to leave the area.

It had burned nearly 5.5 square miles by Monday night.

The county sheriff and fire chief were assessing damages, and people were at the firefighting command center waiting for information.

The cause of the fire was under investigation, but Bitterroot National Forest spokesman Tod McKay noted there were no recent reports of lightning in the area. The fire was fanned by a combination of warm air and wind and dry trees.

Those who were forced from their homes had to leave quickly, said Mike Jetmore, a builder.

“There was literally no warning,” Jetmore said. “It wasn’t, ‘Tomorrow you might have to leave or tonight you might have to leave.’ It was, ‘Go now!’”

McKay heard propane tanks explode, and some homeowners reported seeing 200-foot flames on trees.

Five helicopters and a plane joined rural fire crews. But heavy smoke kept the aircraft grounded Monday.

Firefighters planned to try to isolate homes from vegetation and trees that could burn them.

The National Weather Service issued a warning for Tuesday, from noon to 9 p.m., for a cold front expected to bring gusty winds and low humidity readings. Strong winds and dry air can make existing fires worse and help new fires spread more quickly.

The American Red Cross set up a shelter at a church in the Hamilton area. People with livestock were allowed to bring their animals to the county fairgrounds.