PRESCOTT, Ariz. -- As this town began to grieve over its 19 lost firefighters, officials said Monday that an investigation into their deaths was already underway as the wildfire that killed them continued to rage.

The Yarnell Hill fire, which killed the elite wildland firefighters from the Prescott-based Granite Mountain Interagency Hotshot Crew on Sunday, remained totally uncontrolled as of midday Monday, officials said.

Authorities said the blaze had grown to 8,374 acres overnight after destroying about 200 buildings in Yarnell, Ariz., which is about 30 miles southwest of Prescott, and that the firefighters’ bodies had been recovered and were on their way to the Maricopa County coroner’s office.

“My heart is breaking,” Gov. Jan Brewer said at a news conference, where she announced that she had signed a state disaster declaration for the fire.

“I can’t even imagine how the families and friends who knew these individuals feel. It’s just unbearable. … For now, as we mourn, consider this: The Yarnell [fire] claimed the lives of more first responders than any single disaster since 9/11.”

The Arizona fire is relatively small compared with some of the West’s worst wildfires, some of which have exceeded 60,000 acres. But the lives it claimed have left an outsized mark on Prescott, population 40,308, as federal officials prepared to take over management of the battle against the blaze.

Well-wishers left flowers and tributes outside the Prescott Fire Department, and alongside Highway 69 headed into Prescott, three women stood holding a sign saying “Our thoughts are with you all.”

Late Sunday night, city and fire officials and the victims’ family members gathered at a local school to grieve and to pray as news of the deaths spread. “There’s probably no greater burden for a fire chief to deal with than talking to families who have lost their loved ones,” a visibly emotional Prescott Fire Chief Dan Fraijo told reporters.

“They’re very strong … but we’re going through an incredible period of grief.”

The fire has almost entirely wiped out Prescott’s wildland firefighting unit, which worked separately from firefighters whose job it was to protect the city. A sole survivor from the unit -- who, like the dead, remains thus far unnamed by officials -- survived while moving equipment to a different part of the fire area, Fraijo said.

That firefighter was hospitalized, but there were no updates on his condition Monday.

Officials have not determined why the firefighters were overrun by the blaze but suggested that high winds played a role in unexpectedly shifting the direction of the fire. Fraijo said the firefighters “were in the position of protecting property when something tragic took place, that maybe Mother Nature will only be able to explain.”

“Whatever may have happened," Fraijo said, "we will be able to take that terrible tragedy and build on that."

Previous incidents in which more than 10 firefighters were killed in wildfires have resulted in safety investigations, as well as training and policy changes for wildland crews.

Calls expressing support for the community have already begun pouring in from across the country and around the world.

Mayor Marlin Kuykendall said he’d received condolences from President Obama and Sen. John McCain, among many others.

“I’ve probably gotten 150 texts from people I don’t even recognize their names, expressing condolences, some from other countries,” Fraijo said. “The outcry for help has been incredible.”

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