"We grieve for the family. We grieve for the department. We grieve for the city," Prescott Fire Chief Dan Fraijo said at a news conference Sunday evening. "We're devastated. We just lost 19 of the finest people you'll ever meet."
Reichling said that crews died when the winds turned around and they were caught in a bad situation. He said it was a catastrophic situation with dry vegetation fueling the fire.
"This fire was very radical in its behavior, the fuels were very dry, the relative humidity was low, the wind was coming out of the south, it turned around on us because of monsoon action this afternoon," Reichling said. "That's what caused the deaths, the change in the radical behavior of the burning fuels."
The "hotshot" firefighters were forced to deploy their fire shelters -- tent-like structures meant to shield firefighters from flames and heat -- when they were caught near the central Arizona town of Yarnell, state forestry spokesman Art Morrison said.
Reichling said it is the biggest firefighter casualty in our state's history. It's also the deadliest in the U.S. for at least 30 years.
One member of the Granite Mountain Hotshots survived, Prescott Fire spokesman Wade Ward said.
That crew member was working in another location.
The crew killed in the massive blaze had worked other wildfires in recent weeks in New Mexico and Arizona. The unit was established in 2002.
The wildfire that sparked just southwest of Prescott after an apparent lightning strike grew from four acres to more than 6,000 acres Sunday, forcing the evacuation of several communities.
Reichling said of the 500 structures in Yarnell, including homes, business and sheds, half of them have been destroyed in the fire. No structures in Peeples Valley have been affected as of yet.
Reichling said there are currently 250 firefighters working the Yarnell Hill Fire, and between 200 and 250 more would be coming in.
He said there were four planes working the fire. Fire crews are expected to be on scene for at least a week.
Officials said the fire is burning west of State Route 89, between Yarnell and Peeples Valley, and as more resources are being called in, evacuation centers have been set up at Yavapai Community College and Wickenburg High School.
As of 4 p.m. on Sunday, residents of the Model Creek Subdivision homes, the Double Bar A Ranch and the Buckhorn subdivision had been ordered to evacuate. In addition, an order to evacuate was issued for Peeples Valley west of State Route 89, north of Yarnell Road and and south of Sorrell Road. Also included in the evacuation order is the town of Yarnell. All were notified by telephone, according to the Yavapai County Sheriff's Office.
Officials say approximately 600 people are under mandatory evacuation. Sheriff's spokesman Dwight D'Evelyn said deputies had completed evacuations and would be maintaining road blocks in the area.
Residents and small animals were initially being evacuated to the Yavapai Community College located at 1100 E. Sheldon in Prescott, Ariz. Large animals are being evacuated to the Hidden Springs Ranch located on Highway 89 just southwest of Hayes Ranch Road.
At 4:30 p.m. the Arizona Department of Transportation said about 15 miles of State Route 89 was closed just north of Congress to south of Kirkland. Drivers traveling northbound can use US 93 or Interstate 17 as alternate routes.
The wildfire is 0 percent contained.
Crews are expecting rain and lightning overnight. They say it can help by bringing moisture to dry land and brush, but lightning could spark more fires.
ABC15 meteorologist Randy Kollins said currently, winds in the area are about 5 to 9 mph, with similar conditions expected on Monday. There is also a 30 percent chance of showers in the area on Monday.
Officials said the Yarnell Valley has been in a drought for about 10 years and the materials fueling the fire are very dry, helping the fire spread fast.
Reichling said the area hasn't had a major fire in 40 years.