Colorado Springs Fire
A helicopter drops water in the forest behind a neighborhood near the Waldo Canyon fire in Colorado Springs Thursday. Reuters

The Colorado Springs wildfire has forced the evacuation of some 35,000 people and destroyed 346 homes, Mayor Steve Bach said Thursday, citing preliminary damage reports.

If those figures prove true, the tally of lost homes in and around Colorado Springs would make the Waldo Canyon Fire Colorado's most destructive on record, surpassing the 257 homes consumed in recent weeks by a much larger blaze in the north, near Fort Collins.

Until Thursday, the High Park fire west of Fort Collins had been the most destructive in state history.

While no deaths or serious injuries have been reported so far, Colorado Springs Police Chief Peter Carey said authorities were seeking the whereabouts of some people he described as unaccounted for, though he did not give a number, Reuters reported.

Police spokeswoman Carrie McCuffland said there were no reports of missing persons, and the unaccounted-for list consists of those who apparently neglected to register with the city or the American Red Cross as evacuees.

Every indication is that there are no casualties, McCuffland told Reuters.

Authorities earlier acknowledged the loss of hundreds of homes in Tuesday's firestorm, but the damage toll released by the mayor at an afternoon news conference on Thursday gave the first firm picture of the full extent of the devastation.

Authorities will meet with evacuated residents Thursday night to tell them the fate of their homes. After that, officials will release maps of the destroyed and damaged residences, the Los Angeles Times reported.

More than 20,000 houses near the city's western edge remain threatened, according to reports from the scene.

President Barack Obama plans to visit Colorado Springs Friday to meet with firefighters and tour the ravaged zones.

The grim news came as lighter winds helped firefighters battling to contain the inferno that had roared unchecked through residential neighborhoods in the northwestern corner of Colorado Springs and nibbled at the fringe of the U.S. Air Force Academy campus.

For the first time since the blaze erupted on Saturday, a red-flag warning for heightened fire hazards was lifted for the Colorado Springs area.

We had a pretty good day on the line today. There was minimal fire growth, incident commander Rich Harvey said.

Cooler weather on Thursday gave firefighters a chance to expand the containment area to 10 percent. The break in the weather also aided fire crews battling the Flagstaff fire, which had threatened Boulder. Containment of that blaze grew to 30 percent.

The Flagstaff fire burned dangerously close to Boulder until a Wednesday evening thunderstorm brought rain and higher humidity. Firefighters put out eight to 10 spot fires caused by lightning strikes but increased containment. All pre-evacuation notices for Boulder have been lifted.