US fire officials have said that a deadly wildfire which claimed the lives of 19 firefighters is now 45 percent under control. The blaze in the state of Arizona has engulfed thousands of acres including large parts of the town of Yarnell.
The Prescott fire chief said his organisation and city were in grief after 19 firefighters from his department died in the wildfire blaze.
We're an organisation and a city that's in grief. We grieve for the families, we grieve for the department and we grieve for the city.
– Prescott Fire Chief Dan Fraijo
Arizona Governor Jan Brewer said the tragedy was "as dark a day" as she could remember.
This is as dark a day as I can remember. It may be days or longer before an investigation reveals how this tragedy occurred, but the essence we already know in our hearts: fighting fires is dangerous work.
US President Barack Obama said the 19 firefighters killed in the Arizona wildfire blaze were "heroes" who "selflessly put themselves in harm's way" to protect fellow citizens.
He said: "Yesterday, nineteen firefighters were killed in the line of duty while fighting a wildfire outside Yarnell, Arizona.
"They were heroes - highly-skilled professionals who, like so many across our country do every day, selflessly put themselves in harm's way to protect the lives and property of fellow citizens they would never meet.
"In recent days, hundreds of firefighters have battled extremely dangerous blazes across Arizona and the Southwest. The federal government is already assisting, and we will remain in close contact with state and local officials to provide the support they need.
"But today, Michelle and I join all Americans in sending our thoughts and prayers to the families of these brave firefighters and all whose lives have been upended by this terrible tragedy."
Nineteen firefighters from an elite team were killed in the Arizona wildfire that has destroyed around 200 houses and forced the evacuation of two small towns near state capital Phoenix.
The tragedy ranked as the greatest loss of life among firefighters from a single wildfire blaze in the US in 80 years, since 29 men were killed battling the Griffith Park fire of 1933 in Los Angeles.
Art Morrison, from the Arizona State Forestry Commission, told CNN the firefighters, who were members of a specially trained "hot shot" team, were killed when they were overtaken by the fast-moving flames.
He said: "In normal circumstances, when you're digging fire lines, you make sure you have a good escape route, and you have a safety zone set up. Evidently, their safety zone wasn't big enough, and the fire just overtook them. By the time the other firefighters got in, they didn't survive."
Prescott Fire Chief Dan Fraijo called the tragedy "one of the worst wildfire disasters that's ever taken place."
He added that one member of the 20-man crew happened to be in a separate location and survived. There was no immediate information on his condition.
Cooling stations have been set up to shelter the homeless and elderly people who cannot afford to run their air conditioners, as a potentially dangerous heatwave blistered parts of western US.
In California, Nevada and Arizona, air-conditioned "cooling centres" were set up in community centres, homeless shelters and libraries, and officials warned residents to avoid prolonged exposure to the searing temperatures.
In Phoenix, emergency shelters are temporarily adding 150 beds in an effort to safeguard hundreds of homeless.
An 'excessive heat warning' for "potentially life-threatening" heat, has been issued by the US National Weather Service as a heatwave blistered western parts of the country.
The agency said on their website: "Excessive heat warnings remain in effect for a large portion of California...Nevada...and Arizona...where daytime highs will yet again dangerously soar well past the century mark and overnight lows will barely drop into the seventies and eighties.
"The south west will be particular hot with several places exceeding 110 degrees. One of the hottest places will be Death Valley, California as temperatures will approach 130 degrees".