Roy Rodriguez and his fire crew were fighting back a blaze in a dried-out canyon outside Los Angeles when the wind suddenly shifted.

The team found themselves trapped by the flames, on the side of a steep hill. Rodriguez scrambled his way to a trail and managed to hide under his fire shelter, letting the flames pass over the aluminum-and-silica cover. His fellow firefighters, however, never made it under their shelter. Two perished, while two others were critically injured.

Memories of that 1993 fire have come flooding back to the Los Angeles County firefighter this week as Americans mourn the deaths of 19 firefighters who were overwhelmed Sunday near Yarnell, Ariz. Like Rodriguez, the elite Hotshot fire crew had taken cover under their shelters, but ended up dying beneath them.

Although the shelters saved his life twice, Rodriguez said he well knows the uncertain protection they provide.

“You don’t want to rely on your fire shelter to get you through something,” Rodriguez said. “It is a last resort. It’s when all else has failed.”

How well such shelters work depends on factors such as the terrain where they’re used and how long the fires burn on top of them, Rodriguez said. His fallen colleagues were never able to reach an appropriate surface where they could deploy their shelters.

“They’re designed to deflect radiant heat,” Rodriguez said. “You do absorb some on the inside. But it all depends on where you’re at, where you deploy them. You have to wait it out.”

Getting through the fire also depends on staying calm as the heat and smoke rage outside, he said.

“You train for those situations. You want to try to get in them and secure yourself in under 30 seconds. Because things are happening right now and it’s not time to think up another plan. You better be in that shelter and hunkered down,” Rodriguez said.

“You try to think of the best but it’s kinda hard with the atmosphere outside. It’s hot, smoky, windy, uncomfortable to say the least. You’re just hoping for the best. You go to your happy place.”