Firefighters made progress Thursday in fighting a blaze that has devoured more than 18,000 acres in Colorado, but their sense of accomplishment was tempered by the news that nearly 350 homes in Colorado Springs had been destroyed by the flames.

Mayor Steve Bach, citing preliminary numbers, told reporters that 346 residences on 34 streets were destroyed.

A meeting was planned Thursday night for residents of specific streets affected by the Waldo Canyon Fire, Bach said.

"This is going to be a tough evening, but we're going to get through it," he said. "This community is going to mount an unprecedented response to this. ... This community is going to surround them with love and encouragement, and we are going to move forward as a city."

The blaze, which has chased 36,000 people from their homes in the city, was estimated to be at 10% containment, incident commander Rich Harvey said.

Calmer winds and lower temperatures Thursday helped firefighters in fighting the blaze.

"The weather cooperated with us today like it has in no other day since this fire started," said Jerri Marr, forest supervisor of the Pike and San Isabel National Forests and Cimarron and Comanche National Grasslands. "We made significant progress today."

Still, she warned, "There's a lot of fire out there on the ground."

The U.S. Forest Service has estimated it could be mid-July before the fire is fully under control.

Colorado Springs Police Chief Pete Carey told reporters, "There's a small number of people we're trying to track down," attempting to determine which evacuation center they might be in and whether they left notifications for relatives. Those number fewer than 10.

A secondary search of the destroyed homes would be carried out Friday, authorities said, to make sure no one remained inside.

The Waldo Canyon Fire captured attention because of its proximity to landmarks such as Pikes Peak and the U.S. Air Force Academy, and also to Colorado Springs, a city of about 400,000, the state's second largest.

The Flying W Ranch, a Western-style tourist attraction in Colorado Springs, burned to the ground.

President Barack Obama will travel to the area Friday to survey the damage and thank responders battling the blaze, the White House said.

Bach said he welcomed the visit. "I really appreciate the president coming here ... if nothing more than just to reassure us that this a focus at a national level, that there are people all over this country who are concerned for our citizens and those who have lost their homes," he said. "And I do plan to ask for cash."

The Denver office of the FBI, meanwhile, has joined local authorities in investigating reports that an arsonist might have set the fire.

"It infuriates me and it just makes my blood boil," Colorado Gov. John Hickenlooper said at the thought of arson. "It creates a physical reaction in me ... to think that there's someone out there, because they get some kick ... there's some joy that they get (from setting a fire)."

Defense Secretary Leon Panetta received a briefing Thursday from NORTHCOM commander Gen. Chuck Jacoby "on the status of Defense Department support" to the wildfires, Panetta's office said, and instructed Jacoby to continue to provide assets to the extent they are needed.

Hickenlooper on Thursday announced the creation of a relief fund to benefit those affected by the fires. Colorado Fire Relief Fund 2012 will assist all communities affected by fires this year and will complement ongoing fundraising efforts online. More than $600,000 in relief support has already been donated, the governor's office said. Individuals can text "fire" to 80000 to donate $10 to the efforts, and several events are planned to benefit the fund.

Carey said police in Colorado Springs have been "inundated" with phone calls from residents wanting to return to evacuation zones. "It's really something we can't do right now, to any further extent," he said.

One frustrated resident showed up at Thursday's press conference on the fire.

A Colorado Springs landmark known for its remarkable geological formations remained closed until further notice.

Garden of the Gods so far has escaped fire damage, said Bonnie Frum, director of operations for its visitor and nature center. But the blaze did reach homes only a few blocks north of the park, she said.

"This is the biggest tragedy our city has ever had," said Frum. "We have a perfect storm going here. A drought with no moisture in the winter. We didn't get a lot of snow. Then the winds and the low humidity. You put it all together, and boy."

She and others said many tourist draws in the area remain open, including Royal Gorge Bridge and Park, Seven Falls and the U.S. Olympic Training Center.

The forecast in the coming days will be somewhat kinder to firefighters.

Temperatures are expected to cool into the lower 90s with winds of no more than 10 mph -- a far cry from the 65-mph gusts Tuesday that whipped the flames through mountain canyons and past containment lines.

The scale of the fire is such that smoke blankets the sky 40 miles to the north, Castle Rock resident Heather Gardner said.

"It's just really devastating to see that landscape completely charred and people's homes lost," she said. "I pray for that community and the rescue workers involved in keeping everyone safe."

The inferno has been a challenge even for some of the country's top firefighters -- sometimes getting the best of them.