A Coulson Aviation air tanker, battling wildfires in Australia, crashed and its three crew members were killed, the company said in a statement.
The plane was a Lockheed C-130, registration number N134CG, which took off from Richmond, New South Wales loaded with retardant for a firebombing mission. It was flying in the Snowy Monario area of southern New South Wales, in the Snowy Mountains.
The company said it is sending a team to assist at the crash site.
"Our thoughts and prayers are with the families of the three crew members aboard," Coulson Aviation said.
Cause of the crash was not immediately known.
The New South Wales Rural Fire Service said the area was experiencing "difficult conditions." At one point, it reported 84 bush or grass fires burning, and about 40 of them had yet to be contained. The service issued several warnings during the day telling people to leave if it was safe to do so. It also advised residents in many areas to stay and seek shelter because it was no longer safe to leave.
The Associated Press reported that three Americans were killed in the crash.
New South Wales Premier Gladys Berejiklian confirmed the deaths and crash in comments to reporters as Australia attempts to deal with an unprecedented fire season that has left a large swath of destruction.
"The only thing I have from the field reports are that the plane came down, it's crashed and there was a large fireball associated with that crash," said Rural Fire Service Commissioner Shane Fitzsimmons.
He said all three aboard were U.S. residents.
"Unfortunately, all we've been able to do is locate the wreckage and the crash site and we have not been able to locate any survivors," he said.
The tragedy brings the death toll from the blazes to at least 31 since September. The fires have also destroyed more than 2,600 homes and razed more than 10.4 million hectares (25.7 million acres), an area bigger than the U.S. state of Indiana.
Coulson grounded other firefighting aircraft as a precaution pending investigation, reducing planes available to firefighters in New South Wales and neighbouring Victoria state. The four-propeller Hercules drops more than 15,000 litres (4,000 gallons) of fire retardant in a single pass.
Australian Transport Safety Bureau, the national air crash investigator, and state police will investigate the crash site, which firefighters described as an active fire ground.
Berejiklian said there were more than 1,700 volunteers and personnel in the field, and five fires were being described at an "emergency warning" level.
Canberra Airport closed because of nearby wildfires, and residents south of Australia's capital were told to seek shelter.
The blaze started Wednesday but strong winds and high temperatures caused conditions in Canberra to deteriorate. A second fire near the airport that started on Thursday morning is at a "watch and act" level.
"Arrivals and departures are affected due to aviation firefighting operations," the airport authority said in a tweet.
Another tweet from traffic police said "the fire is moving fast and there are multiple road closures in the area. Please avoid the area. Local road blocks in place."
Residents in some Canberra suburbs were advised to seek shelter and others to leave immediately.
"The defence force is both assisting to a degree and looking to whether that needs to be reinforced," Defence Minister Angus Campbell told reporters.
-- With files from The Associated Press
