PRESCOTT (AP) - Investigators from across the United States poured into an Arizona town to learn why 19 elite firefighters died in an out-of-control wildfire and whether human error played a role.
The investigation into the country's biggest loss of firefighters since Sept 11, 2001, will look at whether the crew paid attention to the forecast, created an escape route and took other precautions developed after a similar disaster in Colorado nearly two decades ago.
The team also will look at whether the crew should have been pulled out before the fire exploded.
Within hours on Sunday, violent wind gusts turned what was believed to be a relatively manageable, lightning-ignited forest fire into a death trap.
In a desperate attempt at survival, the firefighters unfurled their foil-lined emergency shelters, but those offer only limited protection when in the direct path of a fire.
The lone survivor was serving as a lookout and relaying key information to his colleagues, officials said on Tuesday.
Mr Brendan McDonough, 21, notified the others that the weather was changing rapidly and that the fire had switched direction because of the wind. He told them he was leaving the area and to contact him on the radio if they needed anything, said Mr Wade Ward, a Prescott Fire Department spokesman.
Mr Ward said Mr McDonough "did exactly what he was supposed to". Mr McDonough "has no desire to speak to anybody at this point", he added.
The federal government overhauled its safety procedures following the deaths of 14 firefighters in Colorado in 1994.
"There are so many striking parallels between this tragedy and what happened on Storm King in 1994, it's almost haunting," said Prof Lloyd Burton who specialises in environmental law and policy at the University of Colorado.
Those changes included policies under which no firefighters should be deployed unless they have a safe place to retreat. They must also be continuously informed of changing weather.
The Hotshot team based in Prescott entered the smoky wilderness over the weekend with backpacks, chainsaws and other heavy gear to remove brush and trees and deprive the flames of fuel.
But the blaze grew from 80ha to about 800ha in a matter of hours.
Mr Dick Mangan, a retired US Forest Service safety official and consultant, said it is too early to say if the crew or those managing the fire made mistakes. He said the crew members may have taken too many risks because they were on familiar ground and were trying to protect a community they knew well.
On Tuesday, about 500 firefighters battled the mountain blaze, which had burned about 33 sq km. Yavapai County authorities said about 200 homes and other structures burned in Yarnell, and hundreds of people have been evacuated.
No part of the fire had been contained, and thunderstorms that could bring little rain and lots of lightning remained a major threat, said Ms Karen Takai, a spokesman for the firefighting effort.