Massive wildfires raging across Colorado have destroyed hundreds of homes and forced tens of thousands to flee, but better weather Thursday should help crews beat back the blazes.
"There is not a tool we won't use," fire incident commander Rich Harvey told reporters. "Today we will be incredibly aggressive. We have the horsepower in place."
Summer wildfires are common in the mountains of arid Colorado but rarely burst into residential areas, as the Waldo Canyon Fire did earlier this week, forcing the evacuation of 36,000 people from the Colorado Springs area.
The fire, one of several blazing across the front range of the Rocky Mountains, has torched more than 18,500 acres (7,400 hectares) but there have been no reports of deaths or injuries.
In a sign of the scale of the destruction, US President Barack Obama plans to visit the state on Friday and offered his "thoughts and prayers" on Wednesday to the families impacted and those fighting the fires.
Residents were anxiously awaiting word on whether their homes were safe, but officials warned conditions were still too dangerous for a close assessment.
"I've been evacuated since Saturday. I have no clothes -- nothing," Virginia Caldwell said as she cradled her 18-month-old granddaughter at a Red Cross shelter.
She did not know whether her house was one of the 300 reportedly engulfed by the blaze, and her face was creased with worry.
"I'm up until two and three in the morning," she told AFP.
Artist Colin Gingrich, 38, managed to get his watercolors out of his apartment but had to leave his acrylics.
"I'll have to remember how they looked so I can do them over," he said as he waited for news at the shelter. "I don't have a car so I left with my neighbors... But I did get 50 pieces of art out."
Colorado Springs Mayor Steve Bach said he could not yet provide even a estimate of how many homes were lost, telling reporters Thursday morning only that "hundreds of homes have been destroyed."
About 1,200 firefighters have been battling the blaze, helped by the US military and volunteer organizations in the area.
The blaze has also forced the evacuation of the US Air Force Academy where cadets joined fire crews in protecting their barracks and other buildings as the fire swallowed 10 acres of the academy's land.
"This is absolutely the worst wildfire I've ever seen," said Ernst Piercy, the Academy's fire chief.
The wildfire, which began on Saturday, blew out of control Tuesday afternoon when winds changed directions, whipping up flames and causing them to jump fire lines.
It was not immediately clear what sparked the Waldo Canyon Fire -- which has already caused an estimated $3.2 million in damage and threatens more than 20,000 homes -- but Governor John Hickenlooper suggested it may have been human activity.
"There's suspicion out there that we've got some idiot," he told CNN Wednesday.
The Federal Bureau of Investigation said it was helping local law enforcement to determine whether any of the fires were caused by "criminal activity" but has not opened an official investigation.
While the Waldo Canyon fire remains at only five percent containment, winds died down and humidity rose to the point that a "red flag" warning was withdrawn Thursday for the first time since the blaze began.
Record high temperatures, extremely low humidity and wind gusts of up to 60 miles (100 kilometers) an hour have fueled fires across the American West, where an unusually mild and dry winter left widespread tinder-like conditions.
The High Park Fire, a blaze sparked by lightning some 60 miles northwest of Denver -- and described by the Denver Post as Colorado's second-largest in history -- has eaten through 87,284 acres but is now 75 percent contained.
Firefighters are also working to keep the Flagstaff Fire -- estimated at just over 200 acres -- away from the city of Boulder, home to the University of Colorado.
Several other fires are burning in other parts of the state -- famous for winter skiing and adventure sports -- including the Little Sand Fire, which was sparked by lightning on May 13 and has burned through 23,400 acres of land.
The neighboring state of Utah is also combating a major fire, which burned through more than 6,000 acres of grassland in an area south of state capital Salt Lake City.
More than 8,400 people, 578 fire trucks and 79 helicopters have been deployed to tackle wildfires around the United States, the White House said.