A fast-moving wildfire has prompted the evacuation of up to 40,000 residents near the U.S. city of Denver. The blaze is one of a number burning through the western United States.

Authorities issued the evacuation order Monday as high winds spread flames through the Pike National Forest, 90 kilometers southwest of Denver. The fire has scorched 12,000 hectares of forest and brushland and covered the mountain city with a yellow haze.

The fire was started Saturday by an illegal campfire, and it quickly grew. By Sunday, flames were consuming 200 hectares of land each hour. With more gusty winds predicted, Colorado Gvernor Bill Owens expects the blaze to spread. He said, "Some fire professionals think it may double again in the very near future. So it's a huge challenge. Colorado is, in fact, in a crisis right now."

In western Colorado, another fire has scorched 2,900 hectares and destroyed two dozen homes near the town of Glenwood Springs. That blaze was sparked by an underground fire that has burned along a coal seam for decades.

Further west in California, cooling weather and light winds have given firefighters some help with a wildland blaze near Los Angeles. The fire destroyed nine houses, but is now 90 percent contained.