Investigators were combing the charred Arizona mountainside Thursday to learn more about how 19 highly trained firefighters lost their lives in the deadliest U.S. wildfire in 80 years.
Besides examining the landscape, the investigators were using radio logs, including a mayday call, to recreate the men's final moments before they were overcome by windswept flames Sunday.
Investigators want to know whether the men established an escape route and took other precautions. They say they hope firefighters can apply lessons from the disaster in future fires.
"We're really looking at and piecing together all aspects of the incident," Jim Karels, who is leading the investigation team, told reporters Wednesday. "We'll look at fire behavior. We'll look at fuels."
Fire officials believe that the 19 men, part of an elite crew known as the Granite Mountain Hotshots, deployed personalized fire-retardant cocoons in a last-ditch attempt to survive the flames. A single member of the team made it out alive.
Firefighters are slowly gaining control over the wildfire, which has burned 8,400 acres and destroyed 129 homes north of Phoenix after it was started by lightning last Friday. It was described as 80 percent contained Thursday, up from 45 percent Wednesday. Almost 700 firefighters are battling it, and authorities said they expect to have it fully contained within a week.
Officials described the fire as "low burning" — meaning it isn't burning up treetops and then jumping from tree to tree, making it easier to keep under control. They said it had low potential for growth.
The fire devastated the town of Yarnell, which has a population of about 700. Nearby, the hilltop city of Prescott was cleaning up from a separate fire that burned about 6,700 acres and was described as 96 percent contained.
Prescott pressed on with its well-known July 4 celebration — hotels have long since been booked — but it planned to remember the fallen firefighters in a ceremony before the evening fireworks, which evacuees and relatives of the dead firefighters planned to attend. Almost $1 million has been raised for relatives of the victims.
Firefighters across the country, meanwhile, were also honoring their fallen comrades.
"Every day we come to work, we don't think this could be the last day," said Capt. Tom Schneider with the Yakima, Wash., Fire Department, whose members are wearing black bands around their badges.
"We think about what can we do safely to make sure that we're protecting the community," Schneider told NBC station KNDO of Yakima. "It's sad, a lot of sorrow."
At the July 4 parade in Whiting, Iowa, south of Sioux City, the Hornick Fire Department's float featured 19 fire suits in memory of the Arizona firefighters.
"All firefighters, we're all brothers and sisters, and losing those 19 meant something to all of us," Scott Mitchell, a volunteer with the department, told NBC station KTIV of Sioux City. "So we want to bring it on to everyone else."
M. Alex Johnson of NBC News and The Associated Press contributed to this report.