The bodies of 19 firefighters killed in America's deadliest fire in 80 years have been removed, as experts investigate how they died so suddenly.
All but one of the 20-strong elite team, mostly aged in their 20s, were killed in the Yarnell Hill fire in the state of Arizona on Sunday. They had been tasked with with digging a fire line and creating an escape route.
Officials say the firefighters appeared to have deployed last-ditch protection equipment just before they were engulfed in flames about 120km north-west of Phoenix.
The blaze, which has quadrupled in size, is the most lethal since the September 11 attacks on the the Twin Towers in New York in 2001 in which 340 firefighters died, AFP reports.
As a makeshift memorial grew outside the victims' home station, including American flags and 19 water bottles arranged in a heart shape, Arizona governor Jan Brewer on Monday ordered flags to be flown at half-mast.
President Barack Obama phoned Mr Brewer to pledge federal aid to help learn from the tragedy and deal with the fire. "He also expressed his gratitude to the hundreds of first responders who continue to work around the clock to protect homes and businesses from this deadly blaze," a statement from the White House said.
By Monday, the uncontained fire had ripped through more than 3200 hectares, up from 2,000 late on Sunday, officials said. High winds are expected to worsen the blaze, complicating the task for about 400 firefighters - double the number battling it on Sunday.
The Yarnell Hill wildfire is the worst of several raging across Arizona and comes two weeks after two people died and 360 homes burned down in the state of Colorado's most destructive blaze ever.
Record and near-record temperatures have left much of the US southwest sweltering. Death Valley in California equalled the hottest ever June temperature in America, at 129 degrees Fahrenheit, or 53 degrees Celsius.