Authorities have information that during the blaze, the firefighters deployed their fire shelters. The shelters must be timed well. Set it up too soon, and the heat inside the shelter can become suffocating. Deploy it too late, and the fire is already on top of you.
Wearing gloves, a firefighter will lie on the ground under the shelter, the ground being the only thing keeping the firefighter cool. The shelter will block 100% of the heat from flames and hot gases and 95% of the radiant heat from the flames themselves.
Drivers fleeing the area were chased by dark plumes filling the air. Some evacuees paused to look from afar, wondering if the flames had torched their homes.
The blaze hadn't touched Prescott yet. But like many other fire departments across the state, the Prescott team jumped in to help.
"A hotshot crew are the elite firefighters," state forestry spokesman Art Morrison said. "They're usually (a) 20-person crew, and they're the ones who actually go in and dig the fire line, cut the brush to make a fuel break. And so they would be as close to the fire as they felt they safely could."
"In normal circumstances, when you're digging fire line, you make sure you have a good escape route, and you have a safety zone set up," Morrison said. "Evidently, their safety zone wasn't big enough, and the fire just overtook them."
'Words cant describe the loss'
One of the firefighters -- Woyjeck, the son of a Los Angeles County fire captain -- joined the Prescott unit just three months ago.
Woyjeck, an avid outdoorsman, always wanted to be a firefighter like his father, Joe Woyjeck told "Anderson Cooper 360" on Monday evening.
Joe Woyjeck said he last talked to his son by phone on Sunday morning.
"He said, 'Dad, we got a fire in Yarnell, Arizona. ... I'll give you a call later,'" the elder Woyjeck recalled.
He said it hasn't sunk in yet that he won't get that phone call.
"Words can't describe the loss that our family is feeling right now," Joe Woyjeck said.
Kevin Woyjeck wasn't the only firefighter's son in the Granite Mountain crew. MacKenzie was the son of retired California Department of Forestry and Fire Protection Capt. Mike MacKenzie, according to that department.
'They were heroes'
Department of Homeland Security Secretary Janet Napolitano urged residents in the area to heed local authorities' instructions, while lamenting the loss of so many firefighters.
"Today, our thoughts and prayers go out to the families and loved ones of the 19 firefighters who lost their lives in the line of duty," she said in a written statement. "As thousands of their colleagues continue to fight wildfires across Arizona and the West, the Department of Homeland Security and FEMA are working closely with our federal partners including the Forest Service and the Department of Interior, to support state and local efforts."
President Barack Obama also lauded the efforts of the fallen firefighters, saying their deaths are heartbreaking and "our thoughts and prayers go out" to their families. His administration stands ready to help in any way necessary, he said.
"They were heroes -- highly skilled professionals who, like so many across our country do every day, selflessly put themselves in harm's way to protect the lives and property of fellow citizens they would never meet," he said in an earlier statement.
Brewer, who was to visit Prescott on Monday, said the loss marked "as dark a day as I can remember." She has ordered state flags be flown at half-staff from sunrise Monday to sunset Wednesday, and issued an emergency declaration that will make $200,000 available for response and recovery, while authorizing mobilization of the National Guard, if necessary.
"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," she said.
"When a tragedy like this strikes, all we can do is offer our eternal gratitude to the fallen, and prayers for the families and friends left behind."
Fraijo said the firefighters who died were exceptionally dedicated to their jobs.
"These are the guys that will go out there with 40, 50 pounds of equipment and walk five miles. They'll sleep out there as they try to develop fire lines" to protect homes, Fraijo said.
Before the 19 deaths in Arizona, 43 firefighters had been killed so far in 2013, according to the U.S. Fire Administration. A total of 83 firefighters died last year while on duty.