As a last-ditch effort at survival, Hotshot crew members are trained to dig into the ground and cover themselves with the tent-like shelter made of fire-resistant material, Fraijo said. The hope in that desperate situation is that the fire will burn over them and they will survive.
"It's an extreme measure that's taken under the absolute worst conditions," Fraijo said.
Nineteen fire shelters were deployed, and some of the firefighters were found inside them, while others were outside the shelters, Mike Reichling, Arizona State Forestry Division spokesman, told the Arizona Republic.
Prescott, which is more than 30 miles northeast of Yarnell, is home to one of 110 Hotshot crews in the United States, according to the U.S. Forest Service website. The unit was established in 2002, and the city also has 75 suppression team members.
In 1994, the Storm King Fire near Glenwood Springs, Colo., killed 14 firefighters who were overtaken by a sudden explosion of flames.
President Barack Obama called the 19 firefighters heroes and said in a statement that the federal government was assisting state and local officials.
"This is as dark a day as I can remember," Gov. Jan Brewer said in a statement. "It may be days or longer before an investigation reveals how this tragedy occurred, but the essence we already know in our hearts: fighting fires is dangerous work."
Brewer said she would travel to the area on Monday.
As the blaze spread, people started fleeing, including Chuck Overmyer and his wife, Ninabill. They were helping friends leave when the blaze switched directions and moved toward his property. They loaded up what belongings they could, including three dogs and a 1930 model hot rod on a trailer.
As he looked out his rear view mirror he could see embers on the roof of his garage.
"We knew it was gone," he said.