The firefighter who died Thursday afternoon in Palo Pinto County was 24-year-old Caleb Hamm of Boise, Idaho, fire officials said Friday morning.
Hamm, whose fire team is based in Salt Lake City, Utah, collapsed while working on a fire line northwest of Mineral Wells, officials said.
He was evacuated to a nearby hospital where he was pronounced dead.
An autopsy will be performed but the "extreme heat" was likely a primary factor, officials said. An accident investigation team will investigate the death.
Hamm was a member of the Bureau of Land Management's Bonneville Interagency Hotshot crew. He had been a firefighter for six years, officials said. He was a 2010 graduate of the University of Idaho.
"Our entire organization deeply mourns the death of one of our own," said Robert V. Abbey, BLM's national director in a statement. "His passing gives us pause to consider what truly matters in life. We extend our deepest sympathies and condolences to his family, friends and members of his crew."
George Byrd, spokesman for the Texas Forest Service, said officials were re-emphasizing the importance of staying hydrated to fire crews. Conditions are grueling when temperatures climb into triple digits, he said.
The fire was started July 4 by a lightening strike. It has burned 1,204 acres and was 80 percent contained Friday morning.
Alex Branch, 817-390-7689