Firefighters battled wildfires that 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 15 miles west of Fort Collins, grew to 22 square miles within about a day of being reported and has destroyed or damaged 18 structures.
Strong winds meanwhile, grounded aircraft fighting a 40-square-mile fire near the mountain community of Ruidoso in southern New Mexico. Crews were still working to build a fire line around the blaze, which started on Friday and has damaged or destroyed 36 structures.
It was not immediately clear how many of the structures lost were homes.
In Colorado, the fire sent up heavy smoke, obscuring the sun and creating an eerie, orange dusk in the middle of the day. The smell of smoke drifted into the Denver area and smoke from the fires spread as far away as parts of central Nebraska, western Kansas and Texas.
The latest New Mexico fire is smaller than the Whitewater-Baldy fire - the largest in the state's history - but 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 did not have an exact figure.
Karen Takai, a spokeswoman for crews battling the Ruidoso fire, said smoke was badly affecting the community of Capitan, about five miles north east of the fire.
She said in addition to the communities that have been evacuated, Capitan and others could face evacuation.
Elsewhere, firefighters were battling a wildfire that blackened six square miles 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.
In Colorado, authorities sent nearly 1,800 evacuation notices to phone numbers. About 500 people had checked in at Red Cross shelters. Larimer County sheriff Justin Smith said.
Authorities say it is the worst fire seen in Larimer County in about 25 years. It spread as fast as one and a half miles 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, Sheriff Smith said.
Kathie Walter and her husband helped friends several miles away evacuate from the Colorado fire. When they got home, they were surprised to get a call warning them to be ready to evacuate just in case. But she did not want to wait.
"Smoke was coming in hard. We could not see flames or orange or black smoke. But we didn't need to see anymore. We just said, 'Hey, let's get out of here'," she said.
They evacuated with their five cats and two dogs, but with had a head start - after a wildfire in the area last year, they had left two suitcases packed in their garage.
The blaze also forced the evacuation of 11 wolves from a sanctuary near the fire. KUSA-TV in Denver reported 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, 25 miles south west 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," Sheriff Smith said.
In New Mexico, the mix of timber, dry grass and the steepness of the slopes were making the firefighting efforts more difficult.
The fire was burning in steep, rocky, inaccessible terrain in the White Mountain Wilderness of the Lincoln National Forest, which is home to Smokey Bear, who became the nation's symbol of fire prevention in the 1940s.
More than 300 firefighters were battling the blaze with help from three large air tankers, three heavy helicopters and three Blackhawk helicopters. There were also 100 National Guard troops in Ruidoso.