Prescott Fire Chief Dan Fraijo said the firefighters were part of the city's fire department.

"We're devastated," he said. "We just lost 19 of the finest people you'll ever meet."

US President Barack Obama paid tribute to the men in a statement yesterday.

"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," Obama said as he headed to Tanzania on the final leg of an official tour of Africa with his family.

"Michelle and I join all Americans in sending our thoughts and prayers to the families of these brave firefighters and all whose lives have been upended by this terrible tragedy."

Hot shot crews are firefighters who often hike long distances into the wilderness with chain saws and backpacks filled with heavy gear to build lines of protection between people and fires.

"By the time they got there, it was moving very quickly," Fraijo said of Sunday's fire.

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

"One of the last failsafe 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.

"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 per cent chance that they survive," he said. "It's an extreme measure that's taken under the absolute worst conditions."

The National Fire Protection Association previously listed the deadliest wildland fire involving firefighters as the 1994 Storm King Fire in Colorado. It killed 14 firefighters who were overtaken by a sudden explosion of flames.

The Arizona fire, started Friday by a lightning strike, had spread to 800 hectares by Sunday amid windy conditions and with temperatures reaching 38 degrees Celsius. Officials ordered more than 50 homes evacuated.

The fire destroyed an estimated 200 homes, Morrison said. Dry grass near the communities of Yarnell and Glen Isla fed the fast-moving blaze, which was whipped up by wind and raced through the homes, he said.

The fire still burned early yesterday, with flames lighting up the night sky in the forest above Yarnell, a town of about 700 residents about 135 kilometers northwest of Phoenix. Most people had evacuated from the town, and no other injuries or other deaths were reported.

Chuck Overmyer and his wife, Ninabill, said they lost their, 1,800-square-foot home in the blaze. They were helping friends flee from the fire when the blaze switched directions and moved toward his property.

They loaded up what belongings they could, including three dogs and a 1930 model hot rod on a trailer. As he looked out of his rear view mirror he could see embers on the roof of his garage.