Crews are battling a fast-moving wildfire in northern Colorado.

The blaze has scorched between 2,000 and 3,000 acres and prompted several dozen evacuation orders.

A spokesman for the Larimer County Sheriff's Office says the fire is in the mountainous Paradise Park area about 25 miles northwest of Fort Collins. He says at least 46 structures and likely many more have been evacuated, and an evacuation center has been set up.

No damage or injuries have been reported. The cause of the fire is not yet known.

Two heavy air tankers, a single-engine air tanker and three helicopters are on the scene to help fight the blaze, which appears to be burning on private and U.S. Forest Service land and is being fueled by sustained winds of between 20 and 25 mph.

Firefighters should benefit from cooler weather Saturday evening, but the cold front is expected to bring wind gusts as high as 40 mph.