Meanwhile, authorities in central Utah found one woman dead Tuesday when they returned to an evacuated area, marking the first casualty in a blaze that consumed at least two dozen homes and appears to be taking a turn for the worst.

Throughout the interior West, firefighters toiled in searing, record-setting heat that refused to relinquish its grip, as they struggled to contain blazes in Colorado, Utah and other Rocky Mountain states Tuesday.

Colorado has endured nearly a week of 100-plus-degree days and low humidity, sapping moisture from timber and grass, creating a devastating formula for volatile wildfires across the state and punishing conditions for firefighters.

"When it's that hot, it just dries the fuels even more. That can make the fuels explosive," said Steve Segin, a fire spokesman for the U.S. Forest Service.

All of Utah and much of Wyoming, Colorado and Montana were under a red flag warning, meaning conditions were hot, dry and ripe for fires.