Firefighters reported more advances Monday against the Waldo Canyon wildfire, saying they've stopped the fire's growth and are working on putting out hot spots within its charred 17,920-acre footprint.

"It has not moved. Perimeter growth: nothing," incident commander Rich Harvey said Monday. "Now we're into the mop-up mode."

It was hopeful news for the 3,000 residents who remained under mandatory evacuation orders Monday.

The focus is on getting people back into their homes as soon as possible, said Steve Cox, who is with Colorado Springs Mayor Steve Bach's office.

"In some cases, we're talking days, not weeks," he said.

Evacuation orders for all except the hardest hit areas were lifted by late Sunday for most of the 32,000 residents who were forced from their homes after winds last week whipped the blaze that has been described as the most destructive in state history. The fire killed two people, destroyed nearly 350 homes and damaged dozens more.

The U.S. Forest Service has warned it could be mid-July before the fire is fully under control. As of Monday evening, the fire was 70% contained.

The blaze is one of several Western wildfires that have burned hundreds of thousands of acres in Colorado, New Mexico, Montana, Utah, Wyoming and South Dakota -- where authorities said a U.S. Air Force C-130 assisting in the firefighting effort crashed Sunday night.

The aircraft crashed while fighting the White Draw Fire near Edgemont, South Dakota, the U.S. Northern Command said. No information was available about the crew.

The crash prompted the U.S. Air Force to ground all firefighting equipped C-130 planes. Including the one went down, eight such military planes had been deployed since June 24 to fight wildfires in the Rocky Mountain region -- including in Colorado to combat the Waldo Canyon Fire -- and thus are affected by the order, said National Interagency Fire Center spokeswoman Jennifer Jones.

While hopes were high for further advances, fire crews were mindful of the possibility of erratic gusty winds that could cause a sudden and unpredictable outbreak, incident commander Rich Harvey told reporters.

While crews work to put the fire out for good, investigators are scouring the burned-out landscape for clues to what started the now 17,920-acre fire.

The FBI has joined agents from the Bureau of Alcohol, Tobacco, Firearms and Explosives as well as local authorities to investigate the cause of the fire that began in the early afternoon of June 23 in the Pike National Forest, about three miles west of Colorado Springs.

Federal agents joined the investigation after reports emerged that an arsonist possibly started the wildfire, which has cost more than $11 million to date to fight.

Investigators had not yet come to any conclusions, Lt. Jeff Kramer of the El Paso County Sheriff's Office said Monday.

With most of the evacuation orders lifted, a steady stream of motorists made their way on ash-covered roads to their homes late Sunday.

"We'd ask that (residents return) in an orderly fashion," said Cox, an assistant to the Colorado Springs mayor.

"Our strategy will be that we continue to shrink that focus area down and down, and get people back in their homes as soon as we can."

District Attorney Dan May warned would-be looters that he intends to deal harshly with anyone who tries to loot evacuated homes, promising potential prison sentences of more than two decades for each break-in.

A map released by Colorado Springs officials showed the fire's fury as it hopscotched through neighborhoods, burning some houses, damaging others and, inexplicably, skipping over some.

Lists of addresses put out by local officials spelled out the toll with simple descriptions: "no visible damage," "visible damage" and "total loss."

On streets with names that reflect the city's serene surroundings, Majestic Drive and Mirror Lake Court, the toll was unimaginable with nearly every house damaged or destroyed.

Some returned Sunday temporarily to these streets to survey the damage.

Among them was Susan Solich, who is caring for her four young grandsons after their parents died last year.

She drove onto the street in the Mountain Shadows area where she'd lived for 18 years to find some trees and homes still standing, but not hers.