Firefighters have been fighting wildfires that have spread quickly in parched forests in Colorado and New Mexico, forcing hundreds of people from their homes and the evacuation of wolves from a sanctuary.

The Colorado fire, burning in a mountainous area about 24 km west of Fort Collins, grew to 57 square km on Sunday, within about a day of being reported.

The fire has destroyed or damaged 18 structures there.

Strong winds, meanwhile, grounded aircraft fighting a 104-square-km wildfire near the mountain community of Ruidoso in southern New Mexico. Crews were still working to build a fire line around the fire, which started on Friday and has damaged or destroyed 36 structures.

It wasn't immediately clear how many of the structures lost were homes.

The latest New Mexico fire is smaller than the Whitewater-Baldy fire - the largest in the state's history - but it's more concerning to authorities because it started closer to homes, said Dan Ware, a spokesman for the New Mexico State Forestry Division. He said the number of Ruidoso evacuees was in the hundreds, but he didn't have an exact figure.

Karen Takai, a spokeswoman for crews battling the Ruidoso fire, said smoke is heavily impacting the community of Capitan, about 8 km northeast of the fire.

Elsewhere on Sunday, firefighters were battling a wildfire that blackened 15.5 square km in Wyoming's Guernsey State Park and forced the evacuation of campers and visitors. Cooler weather was helping firefighters in their battle against two other wildfires in southern Utah.

Rapidly spreading flames

In Colorado, authorities sent nearly 1,800 evacuation notices to phone numbers but it wasn't immediately clear how many residents had to leave.

Authorities say it's the worst fire seen in Larimer County, Colorado, in about 25 years.

It spread as fast as 2.4 km an hour on Saturday, skipping and jumping over some areas but burning intensely in trees in others.

Flames were coming dangerously close to deputies who were telling some residents to evacuate, Smith said.

The blaze also forced the evacuation of 11 wolves from a sanctuary near the fire, with a Denver TV channel reporting in that 19 wolves remained behind at the sanctuary, which has underground concrete bunkers known as "fire dens" that can be used by the animals.

The fire is the latest to hit Colorado's drought-stricken Front Range. In March, the Lower North Fork Fire, 40 km southwest of Denver, killed three people and damaged or destroyed more than two dozen homes.

Eight air tankers - including two from Canada - and several helicopters were on the scene to help fight the blaze.

The speed at which the fire has spread has dashed any hopes of containment for the time being.

"These folks are doing everything they can, but Mother Nature is running this fire," Smith, the sheriff, said.

Source: Agencies