Nineteen members of an elite fire-fighting brigade were killed on Sunday by a fast-moving wildfire in the town of Yarnell, Arizona after the blaze they were targeting accelerated, changed directions and trapped the men, officials said.

Well known as a dangerous job, Sunday's tragedy marks the deadliest wildfire incident involving firefighters in over 30 years, according to the Associated Press.

The men, part of a team from the town of Prescott, Arizona called the Granite Mountain Hotshots, were among the most skilled of the units fighting the fires that have ravaged parts of Arizona and New Mexico in recent weeks.

"We grieve for the family. We grieve for the department. We grieve for the city," said Prescott Fire Chief Dan Fraijo at a news conference Sunday evening. "We're devastated. We just lost 19 of the finest people you'll ever meet."

Explaining the conditions that led to the deaths, AP reports:

Hot shot crews are elite firefighters who often hike for miles into the wilderness with chain saws and backpacks filled with heavy gear to build lines of protection between people and fires. They remove brush, trees and anything that might burn in the direction of homes and cities.

The crew killed in the blaze had worked other wildfires in recent weeks in New Mexico and Arizona, Fraijo said.

"By the time they got there, it was moving very quickly," he told the AP of Sunday's fire.

He added that the firefighters had to deploy the emergency shelters when "something drastic" occurred.

"One of the last fail safe methods that a firefighter can do under those conditions is literally to dig as much as they can down and cover themselves with a protective — kinda looks like a foil type — fire-resistant material — with the desire, the hope at least, is that the fire will burn over the top of them and they can survive it," Fraijo said.

"Under certain conditions there's usually only sometimes a 50 percent chance that they survive," he said. "It's an extreme measure that's taken under the absolute worst conditions."

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