Krista Kennell / AFP - Getty Images Juliann Ashcraft, left, cries alongside a friend, outside of the Granite Mountain Hotshot fire station in Prescott, Ariz., on July 1.

Governor Jan Brewer says her heart is breaking over the unimaginable loss of the firefighters, and for their families, friends and community.

Arizona authorities struggled for answers Monday after 19 highly trained firefighters were trapped and killed by a windblown wildfire — a blaze the governor vowed to stop “before it causes any more heartache.”

One day after the worst loss of life for an American fire department since Sept. 11, investigators said they had not figured out why the men were unable to retreat to a safe zone or otherwise survive the inferno.

“For now, we mourn,” Gov. Jan Brewer said.

Those killed include firefighters Kevin Woyjeck, Chris MacKenzie, and Andrew Ashcraft.

Woyjeck, 21, and MacKenzie, 30, were both originally from Southern California, according to NBC Los Angeles. Woyjeck was the son of Los Angeles County Fire Capt. Joe Woyjeck, the website reported.

“He was doing everything he could to become a professional firefighter – he had an extreme work ethic,” L.A. County fire inspector Keith Mora told NBC Los Angeles, referring to Woyjeck. “He was a great, great kid. I say ‘kid,’ but he was a young man at 21 years old.”

Juliann Ashcraft told the website of The Arizona Republic and NBC affiliate KPNX that she and her four children were watching the news when they learned her husband, Andrew, 29, was among the dead.

“They died heroes,” she said through tears. “And we’ll miss them. We love them.”

Monday evening the city of Prescott, Ariz. released the names of the other 16 victims: Anthony Rose, 23; Eric Marsh, 43; Robert Caldwell, 23; Clayton Whitted , 28; Scott Norris, 28; Dustin Deford, 24; Sean Misner, 26; Garret Zuppiger, 27; Travis Carter, 31; Grant McKee, 21; Travis Turbyfill, 27; JesseSteed, 36; Wade Parker, 22; Joe Thurston, 32; William Warneke, 25; and John Percin, 24.

The fire, sparked by lightning on Friday, raged uncontrolled for a fourth day. By afternoon it had destroyed more than 200 buildings in Yarnell, a town of about 700 people northwest of Phoenix. It was described as at least 13 square miles and “zero percent” contained, though more than 400 firefighters were trying.

The wildfire claimed all but one member of the Granite Mountain Hotshots, a team of elite firefighters known for extensive training and a demanding fitness regimen. Officials said only that the survivor might have been repositioning equipment.

Wade Ward, the public information officer for the Prescott Fire Department in Arizona, talks about the tragic loss of 19 firefighters in a massive wildfire, saying "it had to be the perfect storm in order for this to happen."

“We can honor their service with our gratitude and prayers,” Brewer said, “and through our steadfast dedication to do whatever is necessary to bring this fire under control before it causes any more heartache.”

Brewer ordered that flags at state buildings and facilities be lowered to half-staff from sunrise Monday until sunset Wednesday in honor of the fallen firefighters, according to the governor's website.

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Mary Rasmussen, a spokeswoman for Prescott National Forest, said it appeared the 19 were engaged in a “direct attack” — getting close to the fire and trying to create a break to starve it of fuel.

She described the maneuver as “one foot in the black and one foot in the green,” and said it was only done when the flames were 5 feet high or less: “They’re right up against it.”

The conditions Sunday were extreme, with unusual wind, she said, and authorities were checking what other factors might have contributed.

Temperatures soared into the 110s in Arizona over the weekend, and National Weather Service meteorologist Brian Klimowski told The Associated Press that there was a sudden increase and shift in the wind at about the time the men were lost Sunday afternoon.

Art Morrison, a state forestry spokesman, told The Associated Press that the men had been forced to deploy emergency fire shelters — individual, portable cocoons meant to protect breathable air and shield them from the heat.

Tom Harbour, national fire director for the U.S. Forest Service, said the shelters had saved hundreds of lives over the years. But he said some fires are strong enough, and move quickly enough, to overwhelm them. The fire was the deadliest wildfire in the United States in 80 years.

From the few known details, he said it was not clear that anyone did anything wrong.

“It’s way, way too early to be drawing any conclusions,” said Harbour, who said he had not seen anything like this fire in his 44-year career. “The only conclusion right now is that souls are dead and half the town of Yarnell is gone.”

Slideshow: Arizona blaze kills 19 elite firefighters David Kadlubowski / The Arizona Republic via AP Nineteen firefighters - all members of an elite response team - were killed Sunday battling a fast-moving wildfire in Arizona, marking the deadliest single incident for firefighters since the Sept. 11, 2001, attacks, officials said. Launch slideshow

Hotshot fire crews often hike into the wilderness lugging 40 or 50 pounds of equipment, including chain saws and other heavy gear, to clear brush and trees and anything else that might feed the flames.

The Granite Mountain crew had battled blazes in New Mexico and elsewhere in Arizona in recent weeks.

“If you ever met them, you would meet the finest, most dedicated people,” Prescott Fire Chief Dan Fraijo said. “They’ll sleep out there as they try to develop fire lines and put protection between homes and natural resources and still try to remain safe.”

President Barack Obama, in a statement, described the fallen men as “heroes,” and Arizona Gov. Jan Brewer said it was “as dark a day as I can remember.” Arizona Sen. John McCain said the men’s sacrifice would not be forgotten.

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