PRESCOTT, Ariz. -- As the Yarnell Hill Fire continues to rage uncontrolled, Arizona officials launched an investigation Tuesday to find out how the fast, erratic wildfire killed 19 hotshot firefighters and whether the tragedy could have been averted.
Fire conditions Sunday were among the most dangerous some experts had ever seen. Low humidity, high temperatures and extremely dry and dense fuel created a worst-case scenario for the crew, which was trapped between two ridges when winds suddenly reversed.
Some of the men had covered themselves with foil-lined, heat-resistant tarps known as fire shelters, but they were unable to survive the blaze. The fire dispatch center was notified at about 4:50 p.m. Sunday that the shelters were deployed, said Carrie Dennett, an Arizona State Forestry Division fire-prevention officer.
The grim scene is the starting point for the state's investigation. It comes as the Forestry Division turned over command of firefighting activities late Monday to a federal fire-management team with broader access to resources and equipment. While the federal government will oversee firefighting, the state will maintain control over the investigation.
By Tuesday afternoon, the Yarnell Hill Fire had grown to 13 square miles and was completely uncontained. As many as 500 firefighters are battling the blaze.
The identities of the Granite Mountain Hotshots, some as young as 21, were disclosed Monday afternoon as the community of about 40,000 people 80 miles northwest of Phoenix mourned. The fire killed about a third of Prescott's sworn firefighters.
The members of the crew, the only hotshot team in the nation from a city fire department, were killed Sunday protecting homes as they battled the Yarnell Hill Fire, about 35 miles southwest of here. It is the worst firefighting tragedy ever in Arizona, and one of the nation's deadliest.
Dennett declined to say when the firefighters died. She said the state agency's investigative team should begin taking shape Tuesday as other fire investigators start their work.
"It will be designed so we can learn from this and teach up-and-coming firefighters if there are any lessons that can be learned," Dennett said. "A lot of firefighters died. We have to do this right and get the right team here. It will take some time."
The investigative team will consist of up to 10 people recruited from around the country from local, state and federal agencies, she said.
The group will include a team leader, a fire-behavioral analyst who can describe how a fire accelerates, a fire-operations specialist, a safety specialist and a person to document the information, said Judith Downing of the U.S. Forest Service. A report will be published when the work is finished.
Downing, who arrived Monday in Arizona with a seven-member National Incident Management Organization team to assist in the operation, said the investigation will be independent.
"Our role is not to do the investigation," Downing said. "Our role is to provide support to the state."
Investigators will want to understand the weather, how the fire behaved, the location of the fire crews and what the vegetation was like. They are expected to sift through troves of records: dispatch logs, standing plans, incident-management decisions, radio logs, historical weather readings, forest clearance schedules - anything to help them understand why so many died and how to prevent it from happening again.
"Hotshot crews always assess the risks before going in. I know, knowing Granite Mountain, they did that. They are as good a crew as is out there," said Dugger Hughes of the Southwest Coordination Center, an interagency organization in New Mexico that coordinates state and federal firefighting resources. He also is a wildland battalion chief whose command includes a hotshot team.
"They knew what they were getting into. It had to be pretty dramatic. I'm anxious to see the report. I want to know what happened," he said, noting that he has fought fires with the men who died. He saw no indication of communications failures.
Although details remain scarce, there are already some indications of key areas of inquiry.
A fire-monitoring station 4 miles from the fire measured nearly record combustion levels for the fuel on the ground. The Energy Release Component reading measures the potential fuel levels. They were in the 97th percentile, meaning the chaparral grass and scrub could release more energy than at almost any time since the station was installed in 1985.
"That reading should make the hairs on the back of any good fire manager's neck stand up," said Rocky Barker, who has written about every fatal fire in the West since 1988 and authored "Scorched Earth: How the Fires of Yellowstone Changed America."
The last fire in the Yarnell area was in 1967, Hughes said, and the area had had no controlled burns since then.
The weather combined with fuel loads to create a deadly combination. Meteorologists at the University of Arizona in Tucson ran models the morning of the fire predicting to within an hour the terrifying conditions the hotshots would confront.
"One model showed 45-knot (52 mph) winds and rapidly changing wind direction. It is a worst-case scenario for firefighting. They were the most dangerous conditions you could have in Arizona," said research meteorologist Mike Leuthold at the university's Institute of Atmospheric Physics.
In the real world, winds from the southwest were gusting at 15 to 25 mph at 4:01 p.m. PST Sunday at the monitoring station near the blaze. An hour later, winds were gusting at 30 to 47 mph from the northeast.
Huddled in a hollow between two ridges were the hotshots.
The worst was coming. During the monsoon - a meteorological event that happens during the summer throughout the Southwest - the searing desert temperatures force columns of hot air high into the atmosphere, Leuthold and National Weather Service meteorologists said.
The higher these plumes climb, the more chance they have for lifting embers and dispersing them widely. They also increase the chance of dry lightning strikes.
On Sunday, meteorologists measured the thermals as high as 22,000 feet, halfway through the atmosphere. The readings were among the highest they'd ever seen. In early fire reports, lightning was blamed for starting the Yarnell Hill Fire on Friday. And in Rim Country and near Prescott, the thunderstorms bring massive downdrafts of air - pushing huge gusts of air and reversing winds.
That's exactly what happened Sunday.
Brian Klimowski, the National Weather Service's meteorologist in chief in the Flagstaff division, said local topography could channel winds into even stronger gusts, making fire behavior more unpredictable.
The Weather Service provides twice-daily fire weather forecasts for each region. In large fires, the service also provides spot forecasts for specific fire locations upon request.
Firefighters did make forecast requests for the Yarnell Hill Fire, which Klimowski's team updated twice a day, he said. In addition, the Weather Service also called firefighters twice Sunday afternoon warning about the likelihood of thunderstorms and high winds.
Weather and fuel loads are certain topics of any fire investigation.
The fire itself was a beast.
"Guys on the ground told me the fire behavior was as extreme as anything they'd ever seen," Hughes said. Early official reports showed flames reached 40 feet high and traveled up to half a mile an hour.
Such conditions are among the factors investigators will consider as they reconstruct the hotshot team's actions and the fire command's decisions.
A parallel investigation is under way to determine precisely what killed the hotshot members. The Yavapai County Sheriff's Office heads up that inquiry though the Maricopa County medical examiner in Phoenix will conduct the autopsies. Yavapai County officials moved the bodies Monday to Phoenix in a solemn caravan because the state's most populous county was better equipped to handle so many casualties. Yavapai County has about 213,000 residents vs. 4 million in Maricopa County.
The Yarnell Hill Fire victims make up the largest mass-casualty event in memory at the Maricopa County morgue, county spokeswoman Cari Gerchick said. Ten pathologists will work on the fire autopsies, the results of which are expected within 48 hours. Full reports are expected within 90 days.
What forensic pathologists find will be important in learning how quickly the fire passed over the Prescott firefighters.
The state has jurisdiction over any investigation into fire fatalities on state land, according to Charlie Gripp, a Federal Emergency Management Agency consultant and a former fire-operations safety officer for the U.S. Forest Service.
"They'll see whether the weather forecast was accurate, and did the crew have the forecast," Gripp said. "They'd been on other fires recently, so they'll look at whether they were adequately rested, were they mentally fatigued."
The Granite Mountain Hotshots had been deployed on a half-dozen other fires, two of them large, in the past two months.
Gripp also said the team also will analyze their fire shelters.
"They can save your life, but they're not designed to survive in front of a blowtorch," Gripp said.
Lynn Bleeker, a former Forest Service firefighter, said the questions investigators will be asking are the obvious ones: "Did they need to be there? With the weather coming in, were they informed as soon as they could have been to get the hell out of there?"
Contributing: Amy B Wang, The Arizona Republic
Craig Harris, Sean Holstege and Bob Ortega, The Arizona Republic