Two NSW volunteer firefighters who died in a tragic accident were both young fathers whose babies were born within days of each other, and were from a “tight-knit” western Sydney volunteer brigade.

A firefighter for 13 years, Deputy Captain Geoffrey Keaton, 32, and firefighter Andrew O’Dwyer 36, both stationed at the Horsley Park Brigade, were in the front seat of a truck in a convoy near the town of Buxton late on Thursday night when a tree fell across the road.

They died when the vehicle flipped and rolled off the road.

Tributes flowed from across the entire firefighting community on Friday, a day when the bushfire emergency continues to affect eastern Australia. There were catastrophic conditions in Adelaide and total fire bans in Victoria and NSW.

The two men and their families socialised with each other, worked together and their wives had much in common.

Friends and fellow volunteers gathered at Horsley Park fire station following the death of 2 volunteers overnight after their truck rolled. Flags are flying at half mast here and around NSW as a mark of respect for Geoff Keaton (32) and Andrew O'Dwyer (36) @abcsydney @abcnews pic.twitter.com/fQxerA0P8R

— James Carmody (@jamescarmody95) December 20, 2019

With Christmas just five days away, NSW RFS commissioner Shane Fitzsimmons, who spent Thursday night with the men’s families, said they were “at a loss”.

Mr Keaton, whose family have a long tradition of volunteer firefighting, and his partner Jess have a son, Harvey. Mr O’Dwyer has a daughter, Charlotte, with his partner Mel. Both children are 19 months old and were born within two days of each other.

“They’re in extraordinary shock and natural despair at the enormity of what’s confronting them and to try and comprehend the tragedy,” Mr Fitzsimmons said.

Three other firefighters were injured in the accident that killed Mr O’Dwyer and Mr Keaton. They freed themselves from the wreckage and were taken to hospital.

In a tragic coincidence, Mr Keaton’s father John was working on the mega blaze at Gospers Mountain, north-west of Sydney, while his son was at the Green Wattle Creek fire.

“Both of these men were very well respected, they were very close, they’re a close-knit brigade, they’re a very community-focused brigade, they work together, socialise together, they’re very interactive together,” Mr Fitzsimmons said.

“Their respective partners and wives shared a lot in common with their camaraderie and connection with the brigade.”

The deaths had shocked the NSW RFS “to the core”, Mr Fitzsimmons said.

“They’re ordinary, everyday individuals – like you and I – that go out and simply want to serve and protect and make a difference in their local community, and they don’t ever go out in the knowledge that they might not come home from that shift,” he said.

Tributes flowed into the NSW RFS Facebook page on Friday for the two firefighters. The Horsley Park Rural Fire Brigade page posted a poem ending with “forever in hearts, always in our memories”.

“This is heartbreaking,” said one post. “The death of ‘brothers’ on active duty has, and always will, rock me to the core,” said another.

Victoria’s firefighting community rally

In Victoria, the state’s firefighting community joined their NSW counterparts in mourning the deaths.

“Our CFA crews have been honoured to fight alongside the RFS these past few months and our deepest sympathies go out to the family, friends and colleagues of these two members,” the Country Fire Authority’s Steve Warrington said.

More than 100 Victorian firefighters are helping with the NSW effort.

Meanwhile, Prime Minister Scott Morrison, who is returning from a trip to Hawaii with his family, issued a statement on Friday morning saying the men were “bravely defending their communities with an unmatched spirit”.

“I express my sincere condolences and sympathies to the families of the firefighters who have so tragically been killed overnight.

The deaths of Mr Keaton and Mr O’Dwyer came at the end of an exhausting day during which it’s feared some 40 homes were lost in Buxton, Balmoral, Bargo and surrounding areas as the Green Wattle Creek blaze tore through the Wollondilly Shire.

RFS crews at a property in Buxton as the Green Wattle Creek Fire continued to threaten communities south-west of Sydney. Photo: AAP

NSW Premier Gladys Berejiklian said the two firefighters represented thousands of volunteers putting their lives at risk to fight fires.

“I can imagine the shock they’re going through and the ripple effect it is going [to have] with the volunteers,” she told the Seven Network.

Also on Thursday, three firefighters were treated for burns after their truck at the Green Wattle Creek blaze was enveloped by flames.

That blaze remained at emergency warning level early on Friday, along with the Gospers Mountain fire.

The neighbouring Kerry Ridge blaze and a fire on the NSW South Coast at Currowan were downgraded to “watch and act” alerts.

The RFS has said officially that 20 structures might have been lost on Thursday, although that number might double. It is now known how many of those are homes.

‘Mega-fire’ continues to burn

Crews also continue to fight the 420,000-hectare Gospers Mountain blaze after a southerly wind change drove flames toward Bell in the upper Blue Mountains.

Firefighters hoped to make the most of lower temperatures across NSW on Friday before extreme weather returns on Saturday.

Bureau of Meteorology acting NSW manager Jane Golding said the next 24 hours would be cooler but the state would heat up again on Saturday.

A week-long state of emergency has been declared in NSW and a statewide total fire ban remains in place.

-with AAP