A volunteer firefighter who died while fighting fires on Monday evening has been named as 28-year-old Samuel McPaul.
Mr McPaul leaves behind his wife, who is pregnant and expecting to have her first child in May.
Mr McPaul died in an accident when the firetruck he was driving rolled at the 26,000-hectare Green Valley fire.
Local crews at the scene described the conditions as a “fire tornado” as cyclonic winds moved across the fire ground.
The NSW RFS Commissioner Shane Fitzsimmons described Mr McPaul as a “much loved and respected firefighter” from the Holbrook area in the Southern Border team.
He described the conditions surrounding the accident as horrific and said his thoughts are with Mr McPaul's family and friends at this time.
"Our thoughts and prayers and our hearts are breaking for Sam's family, for his colleagues in the region and the entire southern border team, but right across the firefighting and emergency services family, to lose one of our own in such extraordinary circumstances is tragic and tragic is an understatement," he said.
The NSW Rural Fire Service says the 10-tonne vehicle was lifted off the ground by extreme winds.
Two male colleagues in the truck - aged 39 and 52 - suffered burns and were taken to hospital.
The 39-year-old colleague on the truck was airlifted to Melbourne’s Prince Alfred Hospital with serious injuries, including burns.
On the same fire ground, another vehicle was enveloped by flames, leaving two firefighters with burns to their face and airways.
The RFS has confirmed that one of those firefighters was sedated and both have been flown to Sydney’s Concord hospital for medical treatment.
On Tuesday morning, five fires were at an emergency level across NSW with five more at a watch-and-act level.
NSW Premier Gladys Berejiklian told reporters the incident was a tragedy and is a reminder of the threat bushfires pose.
"The RFS has lost another member of its family, a young man fighting fires in his local community. He died in very, very difficult circumstances," Ms Berejiklian said.
"This brings home to us what NSW is going through - every fire front is a threat to life, a threat to people's life as they know it."
The incident brings the death toll of volunteer firefighters during this year's catastrophic fire season to three.
Earlier this month, , were killed when their truck rolled near Buxton, south-west of Sydney. Both were fathers of young children and members of the Horsley Park Rural Fire Brigade.
Following the deaths, flags across the state were flown at half-mast as tributes poured in hailing Mr O'Dwyer and Mr Keaton "heroes".
The RFS has confirmed that service flags will be flown at half-mast today as a mark of respect for Mr McPaul.
NSW opposition leader Jodi McKay has also expressed her condolences on behalf of her party.
Prime Minister Scott Morrison said he was "devastated" by the loss of a third volunteer firefighter. "These are testing times. We are so grateful for the courage and dedication of our firefighters," he wrote on Twitter.
Meanwhile, opposition leader Anthony Albanese said the death was a "tragic reminder of the very real dangers out emergency workers face".
The death comes a day after when they are deployed for more than 10 days this fire season.
