More elite teams are being sent to battle an out-of-control inferno that killed 19 firefighters Sunday in the southwestern U.S. state of Arizona.
A sudden wind storm turned the forest fire into one requiring the so-called "hot shot" crew that is trained to fight the fiercest fires. The flames swept over the victims late Sunday as they took cover in foil-lined emergency shelters.
It was the nation's biggest loss of firefighters in a wildfire in 80 years, and the deadliest single day for U.S. firefighters since September 11, 2001.
Officials say the number of firefighters is expected to more than double from the 200 on the scene early Monday.
U.S. President Barack Obama, who is in Africa, issued a statement early Monday calling the firefighters "heroes," and saying his thoughts and prayers were with the firefighters' families during the tragedy.
Arizona Governor Jan Brewer called it "as dark a day as I can remember." She added it may be days or longer before an investigation reveals how the tragedy occurred.
The fast-moving fire near the small town of Yarnell, about 130 kilometers northwest of Phoenix, has burned 34 square kilometers since Friday and destroyed several buildings.
Arizona, and the neighboring western states of California and Nevada are in the middle of an extreme heat wave. Temperatures have reached record highs, and excessive heat warnings are in effect across the region.
Stephen Grady reads notes left at the Granite Mountain Interagency Hotshot Crew fire station in Prescott, Arizona, July 2, 2013.
Linda Lambert places her hand across a plaque hanging on the fence outside the Granite Mountain Interagency Hotshot Crew fire station in Prescott, Arizona, July 2, 2013.
Casen Beyea, 3, wearing a toy fireman helmet looks at the cross for Andrew Ashcrast with his mother Christine at a memorial in Prescott, Arizona, July 2, 2013.
Karis Ashby, a local resident, puts up a thank you sign to firefighters in Congress, Arizona, July 1, 2013, a day after an elite squad of 19 Arizona firefighters were killed in the worst U.S. wildland fire tragedy in 80 years.
A photo of Wade Parker, one of 19 firefighters who died battling a fast-moving wildfire, is displayed at a makeshift memorial in Prescott, Arizone, July 1, 2013.
An aerial view of a section of the town of Yarnell, Arizona destroyed by a wildfire that ripped throught the town, July 1, 2013.
The Granite Mountain Interagency Hotshot Crew is shown in this undated handout photo provided by the City of Prescott, Arizona, July 1, 2013.
Firefighters embrace as a group during a memorial service in Prescott, Arizona, July 1, 2013.
A tribute message for firefighters is displayed on the windows of a coffee shop in Prescott, Arizona, July 1, 2013.
A wildfire burns homes in Yarnell, Arizona, June 30, 2013.
In this photo shot by firefighter Andrew Ashcraft on June 30, 2013, members of the Granite Mountain Hotshots watch a growing wildfire that later swept over and killed the crew of 19 firefighters near Yarnell, Arizona.