(CNN) -- Joe Woyjeck last talked to his son Kevin, the outdoors enthusiast who took up his father's firefighting profession, on the phone just hours before Kevin died.
"He said, 'Dad, we got a fire in Yarnell, Arizona. ... I'll give you a call later,'" the elder Woyjeck told "Anderson Cooper 360" on Monday.
Joe Woyjeck is having a hard time accepting that he won't get that return call.
Kevin Woyjeck, 21, was one of 19 members of an elite Arizona firefighting unit who died Sunday while battling the Yarnell Hill wildfire, which has consumed more than 8,400 acres northwest of Phoenix.
The deaths are under investigation, but officials have said it appears the 19 were forced to lie down under fire shelters -- blankets meant to protect against flames and heat -- as a last resort against an inferno that overwhelmed them.
Kevin, following in the footsteps of his father, a Los Angeles County Fire Department fire captain, joined the Prescott Fire Department's Granite Mountain Hotshots just three months ago, Joe Woyjeck said.
He appeared suited for a hotshot crew, a group of top-shelf wildfire battlers who are called to get close to the blaze, dig barriers and clear out the brush and other material that otherwise would fuel it.
"Always wanted to be a fireman. He loved the outdoors -- sleeping in the dirt was not a big deal to him; he actually enjoyed it, I think," Joe said, remembering a son who always had a fishing rod in his car. "Just a great kid, not a mean bone in his body ... always looking forward to becoming a firefighter like his dad.
"Words can't describe the loss that our family is feeling right now."
Kevin Woyjeck wasn't the only firefighter's son in the Granite Mountain crew. Christopher MacKenzie, 30, was the son of Mike MacKenzie, a retired captain for the California Department of Forestry and Fire Protection.
The Granite Mountain Hotshots were a largely youthful group -- 14 were in their 20s. The eldest, unit superintendent Eric Marsh, was 43.
Also killed Sunday were: Andrew Ashcraft, 29; Robert Caldwell, 23; Travis Carter, 31; Dustin Deford, 24; 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; and Garret Zuppiger, 27.
"It's a younger man's game," Prescott Fire Chief Dan Fraijo told reporters Monday. "These people keep themselves in exceptional condition, they have considerable weight to carry, and they walk (miles) to get to strategic locations."
The physical challenge appealed to Ashcraft, a father and husband who wanted to be a firefighter since middle school.
Ashcraft "wanted to do hotshot work until he physically no longer could do it" and trained feverishly, said his mother, Deborah Pfingston.
Deployed for the summer, the group missed their families but enjoyed the camaraderie, Pfingston told CNN on Monday.
"They loved each other. It was almost a band of brothers. These guys ate together, they slept on the ground together when they were fighting fires -- these were his comrades," she said.
The group's website speaks to their fitness: "Environmental extremes, long hours, bad food, and steep, rugged terrain, demand that we train early and often by running and hiking, doing core exercises, yoga, and weight training."
Joe Woyjeck said his son "wanted to be in the weeds, because I started out as a wildland firefighter."
"He worked out as a cross country runner, (but) he didn't even excel in running until he graduated from high school, because he knew the hotshot thing, you had to be the best," he said.
Now, the elder Woyjeck says he and his wife feel stuck in a sleepless nightmare, coming to terms with their loss.
"My wife and I and our daughter and my other son have kind of sheltered ourselves from the exact incident," he said. "When the time is right, we'll dig in and figure out exactly what happened."
CNN's Brian Todd contributed to this report.