The deaths plunged the town into mourning, and Arizona's governor called it "as dark a day I can remember" and ordered flags flown at half-staff.
"We are heartbroken about what happened," President Barack Obama said while on a visit to Africa. He predicted the tragedy will force government leaders to answer broader questions about how they handle increasingly destructive and deadly wildfires.
The windblown, lightning-sparked fire which had exploded to about 13 square miles by Monday morning also destroyed about 50 homes and threatened 250 others in and around Yarnell, a town of 700 people in the mountains about 85 miles northwest of Phoenix, the Yavapai County Sheriff's Department said.
Residents huddled in shelters and restaurants, watching their homes burn on TV as flames lit up the night sky in the forest above the town.
It was unclear exactly how the firefighters became trapped. Southwest incident team leader Clay Templin said the crew and its commanders were following safety protocols, but it appears the fire's erratic nature simply overwhelmed them.
Brian Klimowski, meteorologist in charge of the National Weather Service's Flagstaff office, said there was a sudden increase and shift in wind around the time of the tragedy. It's not known how powerful the winds were, but they were enough to cause the fire to grow in size from 200 acres to about 2,000 in a matter of hours Sunday.
The hotshot team had spent recent weeks fighting fires in New Mexico and Prescott before being called to Yarnell, entering the smoky wilderness over the weekend with backpacks, chainsaws and other heavy gear to remove brush and trees as a heat wave across the Southwest sent temperatures into the triple digits.
As a last-ditch effort at survival, members are trained to dig into the ground and cover themselves with a tent-like shelter made of fire-resistant material, Fraijo said.
"It's an extreme measure that's taken under the absolute worst conditions," Fraijo said.
Arizona Forestry Division spokesman Mike Reichling said all 19 victims had deployed their shelters.
The flames apparently enveloped the fire shelters. Autopsies were scheduled to determine how the firefighters died.
Gov. Jan Brewer's voice caught several times as she addressed reporters and residents at Prescott High School.
"I know that it is unbearable for many of you, but it also is unbearable for me. I know the pain that everyone is trying to overcome and deal with today," she said.
On the bleachers, two women held each other and wept into tissues. An elderly man clutched a wooden walking stick and gazed at the ground. Many of the residents were red-eyed, and listened with their hands over their mouths.
A makeshift memorial of flower bouquets and American flags formed at the Prescott fire station where the crew was based. Prescott resident Keith Gustafson showed up and placed 19 water bottles in the shape of a heart.
"When I heard about this, it just hit me hard," he said. "It hit me like a ton of bricks."
Hotshot crews go through specialized training and are sent in to battle the nation's fiercest wildfires. Sometimes they hike for miles into the wilderness with heavy gear to build lines of protection between people and fires. They remove anything that might burn in the direction of homes and cities.
More than 200 firefighters and support personnel were assigned to the wildfire as of Monday morning. They included 18 hotshot crews from around the country. Such crews typically have about 20 members each. The number of hotshot crews assigned to the fire is expected to at least double, Reichling said.
The U.S. has 110 hotshot crews, according to the U.S. Forest Service website.
Arizona is in the midst of a historic drought that has left large parts of the state highly flammable.
"Until we get a significant showing of the monsoons, it's show time and it's dangerous, really dangerous," incident commander Roy Hall said.
The National Fire Protection Association website lists the last wildland fire to kill more firefighters as the 1933 Griffith Park fire of Los Angeles, which killed 29. The biggest loss of firefighters in U.S. history was 343, killed in the 9/11 terrorist attack in New York.
In 1994, the Storm King Fire near Glenwood Springs, Colo., killed 14 firefighters who were overtaken by a sudden explosion of flames.
Television aerial video footage showed law enforcement vehicles patrolling Yarnell, driving streets with burned buildings on both sides.
As the blaze spread, people started fleeing, including Chuck Overmyer and his wife, Ninabill. They were helping friends leave when the blaze switched directions and moved toward his property. They loaded up what belongings they could, including three dogs and a 1930 hot rod, on a trailer.
As he looked out his rear-view mirror he could see embers on the roof of his garage.
"We knew it was gone," he said.
He later went to the Arrowhead Bar and Grill in nearby Congress, where he and other locals watched on TV as the fire destroyed his house.
The Red Cross opened two shelters in the area one at Yavapai College in Prescott and the other in a high school gym.
Billeaud reported from Phoenix. Associated Press writers Brian Skoloff in Yarnell and Martin Di Caro in Washington also contributed to this report.
Bodies of firefighters killed in Arizona recovered
The bodies of 19 members of an elite firefighting crew killed after being overrun by an Arizona wildfire have been retrieved from the mountain where they died.
Prescott Fire Chief Dan Fraijo now says all 19 were from the Prescott-based Granite Mountain Hotshots. Authorities earlier said one of the men wasn't a crew member.
One man who belonged to the 20-person team survived because he was moving the crew's truck.
The crew was found late Sunday afternoon with their emergency fire shelters deployed. They'd been battling a blaze moving toward Yarnell, a small town about 85 miles northwest of Phoenix.
The bodies were retrieved Monday near the town.
The fire made it into Yarnell and destroyed an unknown number of homes and businesses. It has burned more than 13 square miles. A look at deadly U.S. accidents involving fire crews
Here is a look at some of the deadliest U.S. tragedies to have claimed the lives of wildland firefighters, including the 19 killed in an Arizona blaze Sunday:
June 30, 2013: Nineteen members of an elite crew are killed in a fire northwest of Phoenix that lit up the night sky in the forest above the town of Yarnell. The fast-moving blaze fueled by hot, dry conditions is the deadliest wildfire involving firefighters in the U.S. for at least 30 years.
Aug. 5, 2008: Nine people were killed when a helicopter crashed shortly after taking off with a load of firefighters heading back to camp in Northern California. Seven of the dead were firefighters with Grayback Forestry Inc. The crew was fighting a forest fire on the Shasta-Trinity National Forest outside Redding, Calif.
Aug. 24, 2003: Eight contract firefighters who had spent two weeks fighting an Idaho wildfire were killed on their way home when their van collided with a tractor-trailer and exploded into flames outside Vale, Ore. The firefighters, all men, worked for First Strike Environmental, a contract firefighting company and all were from Oregon.
July 6, 1994: A blaze near Glenwood Springs, Colo., killed 14 firefighters who were overtaken by a sudden explosion of flames. The lightning-sparked Storm King Mountain blaze roared through shrubs as the firefighters scrambled uphill. Thirty-five firefighters on the mountain that day survived.
June 26, 1990: The rapidly spreading Dude fire in the Tonto National Forest near Payson in eastern Arizona trapped 11 firefighters, killing six of them.
July 9, 1953: The Rattlesnake fire in Southern California took the lives of 15 firefighters battling a blaze in Mendocino National Forest.
Aug. 5, 1949 The Mann Gulch fire near Helena, Mont., killed 12 smokejumpers and a forest ranger after they were overrun by flames. Their story was memorialized in the book "Young Men and Fire" by Norman Maclean, who also wrote "A River Runs Through It."
Oct. 3, 1933 The Griffith Park wildfire in Los Angeles killed 29 firefighters.
Online: National Fire Protection Association, nfpa.org