By the time the flames had passed, 19 men lay dead in the nation’s biggest loss of firefighters in a wildfire in 80 years.

The tragedy Sunday evening all but wiped out the 20-member Granite Mountain Hotshots, a unit based in the small town of Prescott, Prescott Fire Chief Dan Fraijo said as the last of the bodies were retrieved from the mountain. Only one member survived, and that was because he was moving the unit’s truck at the time, authorities said.

The deaths plunged the town into mourning, and Arizona’s governor called it “as dark a day I can remember” and ordered flags flown at half-staff.

“We are heartbroken about what happened,” President Barack Obama said while on a visit to Africa. He predicted the tragedy will force government leaders to answer broader questions about how they handle increasingly destructive and deadly wildfires.

The lightning-sparked fire — which had exploded to about 13 square miles by Monday morning — destroyed about 50 homes and threatened 250 others in and around Yarnell, a town of 700 people in the mountains about 85 miles northwest of Phoenix, the Yavapai County Sheriff’s Department said.