A Canadian-US aerial firefighting company has named the three Americans killed in an air tanker crash on Thursday in south-east New South Wales.

Key points: The three American men who were killed in the crash were aged 44, 42 and 43 years old

The three American men who were killed in the crash were aged 44, 42 and 43 years old They had experience in the Air National Guard, Marine Corps and US Air Force

They had experience in the Air National Guard, Marine Corps and US Air Force The aerial firefighting company expressed condolences and thanked the public for their support

In a post to Facebook, Coulson Aviation (USA) named captain Ian McBeth, first officer Paul Hudson and flight engineer Rick DeMorgan Jr as the aerial firefighting crew who died in the crash of the C-130 Large Air Tanker north-east of Cooma.

The company said its deepest condolences were with the family and friends of those who died.

The Rural Fire Service (RFS) was leasing aircraft from the North American company to help fight bushfires.

The statement said 44-year-old captain McBeth lived in Great Falls, Montana, and was a highly respected C-130 pilot and qualified instructor with experience fighting fires both in the military and with the aviation company.

He served with the Wyoming Air National Guard and was later a member of the Montana Air National Guard.

"Ian's love for his wife [Bowdie] and children [Abigail, Calvin, and Ella] was evident for anyone who spent time around him," Coulson Aviation said in a statement.

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First officer Hudson, 42, from the United States Marine Corps, lived in Buckeye Arizona and had 20 years of service in the US Marines.

He is survived by his wife Noreen, who lives in Arizona.

Mr DeMorgan Jr, 43, from Navarre, Florida, served in the US Air Force with 18 years as a flight engineer on the C-130.

"Rick's passion was always flying and his children [Lucas and Logan]," the statement read.

The statement said the company's crews on other aircraft would be returning to work soon.

"We must continue to work with emergency services to protect local communities," the statement read.

The C-130 which crashed while fighting a bushfire in southern NSW. ( AAP Image: Dan Himbrechts )

The company thanked members of the public for their support in the wake of the fatal crash.

"We are incredibly moved by the outpouring and support from those in Australian and around the world," the statement read.

"Thank you for recognising the work that our crews do and for expressing your condolences and grief for the families of our fallen heroes."

Space to play or pause, M to mute, left and right arrows to seek, up and down arrows for volume. Watch Duration: 38 seconds 38 s Aerial footage of the crash site

Mr DeMorgan Jr was described as a "a true American hero" in a Facebook post by his cousin Pattsy Garnett.

The office of the Governor of California tweeted that they were "heartbroken to learn of the air tanker crash in Australia that claimed the lives of 3 heroic American firefighters".

The California Department of Forestry and Fire Protection extended "heartfelt condolences", tweeting: "Although they didn't wear the Cal Fire patch, they were committed to protecting lives & their loss is felt deeply."

NSW Police said they hope to recover the bodies from the crash site today.