KJZZ

Nineteen firefighters died Sunday in the Yarnell Hill Fire, even though they were using protective fire shields. The devices are a last resort in life-threatening situations.

Phillip Maldonado, a squad leader with the Granite Mountain Hotshots, helps crew member learn the finer points of setting up emergency fire shelters in April 2012. (Photo courtesy of Connor Radnovich-Cronkite News Service)

Fire shields, which are made of fiberglass and foil and look like thin, silvery blankets, have been mandatory since the 1960s. The U.S. Forest Service estimates they have been deployed over 1,200 times, and before Sunday’s tragedy, only about 20 firefighters had died while using them.

Apache Junction Batallion Fire Chief Richard Ochs said the shields’ effectiveness can vary greatly.

"People seem to think that you’re very well protected inside of those shelters and truthfully, you’re still going to come out with significant injuries. You can come out with severe burns, including third-degree burns, because the radiant heat is still going to come through to some degree," Ochs said.

Ochs estimated the shields can deflect 80 percent to 90 percent of a wildfire’s heat, but the effectiveness breaks down when exposed to open flames, and that is why firefighters are taught to only use the shelters as a last resort.

Retired wildland firefighter Jim Paxon knows what it feels like to make that choice. While fighting a fire in 1977, a blaze was headed straight for him and changed directions just before he pulled the shelter over himself.

"I don’t talk about when I did that, you know. It’s such a life changing event," Paxon said.

Perhaps because of this, the U.S. Forest Service has created several videos and pamplets detailing real-life experiences of firefighters who have used the shelters.