Three firefighters died Saturday and two were burned in a blaze sweeping the Utah-Colorado border, the U.S. Wildland Fire Service said in a statement.

The crew was helping fight the Knowles and Gore wildfires, the statement said. Several agencies have deployed firefighters to western Colorado, where those fires merged with the Snyder fire and have devoured 28,000 acres.

Flames suddenly overwhelmed the federal firefighters, who tried to take shelter amid the heat and smoke, the Department of Interior said in a statement.

“The U.S. Wildland Fire Service stands united with the U.S.D.A. Forest Service in grief and in our unwavering support for the loved ones left behind,” the agency said in a statement. The agency did not identify the victims.

Wildfires over the past week have charred the Southwest, where warmer winters, low snowpack and high winds have turned the arid landscape into fuel. Fires have reached into Colorado, Arizona, New Mexico and Nevada.

As of Sunday morning, 11 large wildfires raged in Utah, blackening more than 208,000 acres. The largest is the Cottonwood fire, which started near the city of Beaver, in the southwestern part of the state.

That blaze has grown to at least 92,000 acres in a week, with none of it contained, according to the state of Utah. Gov. Spencer Cox called it the “most destructive fire in the state’s history” in terms of property loss. No injuries or deaths have been reported.

Firefighters on the ground and in the air had to pull out on Friday, and scout for safer ways to attack the blaze, the U.S. Forest Service said.

“The conditions that we have on our fire are pretty persistent across the state,” Alyssa Mason, a spokeswoman for Great Basin Team 5, the federal group leading the response, said on Saturday.

Fires can start innocently, she added. A chain dragging behind a truck can set off sparks and ignite roadside brush. State authorities have taken precautions to limit the threat. Last week, Governor Cox signed an executive order temporarily restricting fireworks through the July 4 holiday weekend.

Red flag warnings remain in effect across the Southwest. Winds could reach up to 40 miles per hour and humidity is expected to remain low, according to the National Weather Service.

As smoke has billowed over the mountains and canyons, residents have watched their cabins and campgrounds, homes and infrastructure disappear in the flames.