Transcript for 19 Firefighters Killed in Arizona Wildfire
yarnell. Reporter: This is as close as we are going to get to this fire because the police behind us have stopped us right here and stopped everyone else. This fire about eight miles away but it's unpredictable and dangerous and as we know deadly. This deadly wildfire tripled in size overnight grown from 2,000 acres to more than 6,000 and still zero percent contained. Now, it's the deadliest u.S. Wildfire involving firefighters in 80 years. The fire took the lives of 19 men part of an elite 20-member firefighter team known as the granite mountain hot shots. We're devastated. We just lost 19. Reporter: It's dedicated to stopping wildfires and saving homes. When winds blew it northwest of phoenix seen in this time-lapsed video out of control these hot shots rushed in to fight. Lightning sparked the fire friday and spread quickly to the small town of yarnell among triple-digit temperatures, low humidity and windy conditions. These guys will go out with 40, 50 pounds of equipment and walk five miles. They'll sleep out there as they try to develop fire lines and put protection between homes, natural resources and still try to remain safe. Reporter: The firefighters were forced to deploy their fire shelters, tent-like structures designed to shield flames and heat and keep in breathable air. It's one of the last failsafe methods that a firefighter can use under life-threatening conditions. Amidst the treacherous conditions most of the town's 700 residents were forced to evacuate. I don't know if my home is standing or not? All of a sudden the wind just changed in a matter of seconds and maybe within a minute or two, we were pretty much inhaling smoke. Reporter: The flames lit up the night sky and smoke from the blaze could be smelled for miles. You heard in the story that they use these protective shields. You put your head right here, your feet at the end and lay horizontally on the ground. Inside you would have breathable air but it could get up to 200 degrees on the inside, 500 on the outside, robin.
This transcript has been automatically generated and may not be 100% accurate.