The 28-year-old died on Monday after the truck on which he was being carried overturned in what has been described as a "fire tornado" near Jingellic.

Rural Fire Service commissioner Shane Fitzsimmons has said the 10-tonne truck was hit by winds so extreme at the Green Valley fire that it flipped on its roof.

Two other firefighters, Andrew Godde, 52, and Rodney O'Keeffe, 39, suffered burns. Mr O'Keeffe was airlifted to the Alfred Hospital in Melbourne in a serious condition.

Mr Godde, the Culcairn fire captain, has described Mr McPaul, a Culcairn mechanic and member of the Morven brigade, as a "ripping young bloke".

An RFS member for 35 years, Mr Godde told The Border Mail he had never seen conditions like those the firefighters encountered as they tried to protect a house and herd of cattle on River Road.

"You hear people talk about these fireballs but I've never experienced anything like that before," he said.

"Unfortunately our truck was in the wrong place at the wrong time."

Mr Godde said Mr McPaul had been among the first to volunteer to help fight the Upper Murray blaze on Monday.

"He often said to me if I ever needed someone to help man a truck he would be happy to go," he said.

"I rang him yesterday and he didn't hesitate to go.

"He was a ripping young bloke and the fact that he and his wife are expecting their first child only adds to what is an extremely sad, sad situation.

"It's a young life taken way too soon trying to save the lives and property of others."

Mr McPaul studied at Charles Sturt University in Wagga, where he was also a representative basketball player.

He grew up at Broulee on the NSW south coast.

While living in Wagga, Mr McPaul was a coach, administrator and player, according to Basketball Wagga.

Wagga basketball identity Peter O'Leary described Mr McPaul as a "really nice guy" who was quite a talented basketball player.

"He did a lot of basketball admin work, too." Mr O'Leary said.

"He was a very dedicated sort of person. I couldn't speak more highly of him."

Wagga Heat's Zac Maloney also recalled Mr McPaul's hard work for basketball in the city.

"He put in a lot of time and effort. He was really dedicated to not just the team, but the association and basketball in general," Mr Maloney said.

"He coached a few junior rep teams and played a few years with our senior state league team.

"Sam was always happy to help out with anything that was going on and would always be first to put his hand up and be involved."

Superintendent Patrick Westwood told the media that the "RFS will continue the support of Sam's family over the coming months".

"As everyone would understand this is a very, very sad day for the NSW Rural Fire Service family locally and across the state," he said.

Mr McPaul's wife Megan is expecting the couple's first child in May.

On Tuesday, both NSW Premier Gladys Berejiklian and her Victorian counterpart Daniel Andrews paid tribute to Mr McPaul.