They were part of an elite squad confronting wildfires on the front line, setting up barriers to stop the spreading destruction. But in their unpredictable world, it doesn't take much to turn a situation deadly.
In this case, a wind shift and other factors caused a central Arizona fire, which now spans 8,400 acres, to become erratic, said Mike Reichling, Arizona State Forestry Division spokesman.
Though the deaths are under investigation, the inferno appears to have proved too much, even for the shelters the 19 firefighters carried as a last-ditch survival tool.
"The fuels were very dry, the relative humidity was low, the wind was coming out of the south. It turned around on us because of monsoon action," Reichling told CNN affiliate KNXV. "That's what caused the deaths.
The firefighters -- members of the Prescott Fire Department's Granite Mountain Hotshots -- were killed Sunday while fighting the Yarnell Hill fire, northwest of Phoenix. Among the dead was Eric Marsh, the unit's 43-year-old superintendent.
Also killed, according to the city of Prescott: Andrew Ashcraft, 29; Robert Caldwell, 23; Travis Carter, 31; Dustin Deford, 24; Christopher MacKenzie, 30; Grant McKee, 21; Sean Misner, 26; Scott Norris, 28; Wade Parker, 22; John Percin, 24; Anthony Rose, 23; Jesse Steed, 36; Joe Thurston, 32; Travis Turbyfill, 27; William Warneke, 25; Clayton Whitted, 28; Kevin Woyjeck, 21; and Garret Zuppiger, 27.
The deaths of the 19 -- representing about 20 percent of Prescott's fire department -- devastated the city. Prescott Fire Chief Dan Fraijo, who sent the unit at the request of regional authorities, said he was told that one of the firefighters had radioed they were about to deploy their fire shelters, a sort of aluminum blanket that protects against the flames and heat -- and a measure of last resort.
All he could do was wait. Only heartbreak followed.
"We just lost 19 of some of the finest people you'll ever meet. Right now, we're in crisis," Fraijo told reporters.
A 20th member of the unit was working on an assignment away from his team and survived, Fraijo said.
"He feels terribly, and we all feel terribly. Unfortunately, we have very few words to express that kind of sorrow, but we understood each other. When you take a person in your arms and you hug them, you don't have to say too much," he said.
A tribute to the firefighters grew Monday outside Prescott Fire Station No. 7. Flowers, American flags and signs -- including those reading "19 Great guys gone -- you will be missed" and "Prescott 19 forever in our hearts" -- were placed on or near a fence that separated the station from a road. The tokens also included 19 bottles of water, arranged in a circle.
Also left was a copy of The Firefighter's Prayer, which contains the lines, "And if, according to my fate, I am to lose my life/Please bless with your protecting hand my children and my wife."
Gov. Jan Brewer called the loss "unbearable" during a Monday news conference and said she understood the pain people are dealing with.
"For now, we mourn," she said.
The wildfire, which is considered the deadliest in state history, began Friday near Yarnell, apparently because of lightning strikes, according to Brewer's office and other authorities. The fire wasn't contained at all on Monday morning, and about 200 homes and other structures have burned in the area of Yarnell, a community of about 600 people, the state forestry division said.
About 400 ground personnel and 100 incident-management staff were working to control the fire Monday.
There are no other reported injuries from the blaze, Reichling said.
"As we face the day the highest priority is for the fallen comrades," said Roy Hall, an incident commander with the state forestry division. "We got a lot of hotshot crews in the nation, and they are the elite of the ground firefighters. They're highly trained and highly specialized. They are a younger generation. That's the tragedy of it, that lives would be lost of such a young group."
He added of the fire, "We know that there are values to be protected and efforts that need to be ongoing in this fire. It's a long ways from being over."