19 Firefighters Killed In Yarnell, Arizona, Blaze: How Was The Elite Crew Lost? [VIDEO]

A wildfire believed to have been sparked by a lighting strike in a central Arizona ranch town killed 19 firefighters in the deadliest day for firefighters since the 9/11 attacks. The nearby town of Prescott's fire chief, Dan Fraijo, told reporters on Sunday night that his force had lost "19 of some of the finest people you'll ever meet", adding that his department was "in crisis" after all but one member of a 20-person crew perished. Fraijo told CNN that he did not know the circumstances which caused the firefighters' deaths and declined to speculate, but said that drought conditions and irregular gusts of wind would have made their fight to contain the blaze especially difficult.

"We teach our people to be safe, to take safety precautions," he said. "Sometimes, unfortunately, it just doesn't work out." Fraijo added that the team was made up of exceptionally dedicated fighters. "These are the guys that will go out there with 40, 50 pounds of equipment and walk five miles. They'll sleep out there as they try to develop fire lines" in order to protect others' homes.

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Art Morrison of the Arizona State Forestry Commission told CNN the firefighters were part of a "hotshot crew" of elites who serve as the shock troops of the force. "They're the ones who actually go in and dig the fire line, cut the brush to make a fuel break. And so they would be as close to the fire as they felt they safely could."

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"In normal circumstances, when you're digging fire line, you make sure you have a good escape route, and you have a safety zone set up," Morrison said. "Evidently, their safety zone wasn't big enough, and the fire just overtook them."

Arizona Governor Jan Brewer called it "as dark a day as I can remember" and said that the cause of their deaths might not be immediately revealed.

"It may be days or longer before an investigation reveals how this tragedy occurred, but the essence we already know in our hearts: fighting fires is dangerous work," she said in a statement.

By Sunday night, said incident commander Mike Reichling, the Arizona blaze had spread across more than 6,000 acres of chaparral and grasslands and torched more than 100 structures. A heat wave in the region, with temperatures reaching well into the triple digits, made conditions especially ripe for a blaze of this size.

President Barack Obama eulogized the fighters in a written statement from Africa, saying "They were heroes -- highly skilled professionals who, like so many across our country do every day, selflessly put themselves in harm's way to protect the lives and property of fellow citizens they would never meet."