PHOENIX - The 19 firefighters killed Sunday while trying to protect the town of Yarnell, Ariz., were forced to deploy fire shelters to try and save their lives.
While we don't yet know why those shelters didn't protect the firefighters, we can tell you how they work.
Those shelters are a giant double layered blanket with materials, including aluminum foil, that is used to shield a firefighter from both radiant heat and direct heat, while also allowing him or her to breath air from the ground.
Two years ago, NewsChannel5 Scripps sister station ABC15's Christopher Sign traveled with a group of firefighters to learn more about how the suits work and at what point they begin to fail.
According to the National Wildfire Coordinating Group, these shelters can reflect up to 95 percent of radiant heat, which is the heat that comes from the sun. When direct heat, such as a fire, hits, the shelter can withstand up to 500 degrees fahrenheit.
Once those shelters reach 500 degrees fahrenheit, the glue that holds the shelter's protective layers begins to melt and break down. Therefore the heat inside the shelter is capable of rising very quickly.
In a "worst case scenario," a firefighter has 30 seconds to deploy their shield. The key is creating a seal to keep smoke and ash out. According to ABC15's Sign, who tested the shield, the inside can get as hot as 200 degrees even when it's working properly.
In a YouTube video posted by the National Wildfire Coordinating Group, officials demonstrate how quickly these shelters can be deployed in an effort to save a firefighter's life: