A massive wildfire has swept through a residential area of Colorado’s second most populous city, destroying homes and prompting 32,000 people to flee to safety.

The fire, which began in Waldo Canyon on Saturday, exploded into the Colorado Springs community of Mountain Shadows on Tuesday and set ablaze the mountains that rim the city 100 kilometres south of the state capital, Denver.

“This is a firestorm of epic proportions,” Colorado Springs Fire Chief Rich Brown told a news conference late on Tuesday, before the fire surged again overnight.

Fire reaches houses in the Mountain Shadows area of Colorado Springs. Photo: AP

Among the areas threatened was the US Air Force Academy, which evacuated two housing areas, a day before the scheduled arrival of 1000 new cadets, the academy said.

Soaring temperatures compounded the agony for firefighters trying to contain the 2400 hectare blaze, one of many raging across the American west.

The Waldo Canyon fire has spread quickly since it began on Saturday, and turbulent winds on Tuesday afternoon prompted authorities to seek evacuations of up to 32,000 residents.

Fire from the Waldo Canyon wildfire destroyed homes in Colorado Springs. Photo: AP

There were no reports of anyone killed or wounded in the fire, which is just five per cent contained.

Officials declined to estimate the number of homes destroyed, but feared the figure would be high.

Record high temperatures, extremely low humidity and wind gusts of up to 96.54 km/h have fuelled blazes across the American West.

The state of Utah also is combating a major fire, which burned through more than 2428 hectares of grassland in an area about 45 minutes south of Salt Lake City.

AFP