Australia is to deploy navy ships and army helicopters to help rescue people trapped by devastating wildfires after thousands fled to the beach to escape the flames.

Thousands in Mallacoota, Victoria, sought refuge as blazes threatened to cut off all the escape routes for residents, leaving them stranded.

Around 4,000 people were forced to flee to the beach to escape the flames, while many took refuge on boats.

Image: Thousands of holidaymakers were forced to flee to beaches in fire-ravaged towns

Bushfire turns sky blood-red

The flames roared past the town's airport at 8am and the temperature shot up to 49C (120F), according to newspaper The Age.

The fresh rescue operation comes as terrifying footage emerged of firefighters racing through a bushfire as flames lash their truck.

Video shows the firefighters struggling to see through the smoke as embers rain down and flames surround them.

"We are retreating… fires on the road already," the message over the radio says, as they hold fire blankets in case the heat bursts the windows.

Incredibly, they all survived the incident near Nowra in New South Wales.

The sky in the Victoria town of Mallacoota went black and then dark red as embers landed near people on the beach - many of whom were wearing goggles and breathing masks.

Image: Residents of Mallacoota, Victoria, gathered at the wharf. Pic: @bluesfestblues

People on the beach said they could see houses being destroyed and hear gas canisters exploding.

Country Fire Authority chief officer Steve Warrington said three strike teams were based in the town and were protecting residents.

Helicopter footage shows people escaping to beach

He added: "It is pitch black. It is quite scary in that community. They right now are under threat. But we will hold our line and they will be saved and protected."

The premier of Victoria, Daniel Andrews, said there were plans to evacuate the trapped people by sea.

Just after 4pm local time, Gippsland incident controller Ben Rankin said fire had affected a "significant number of assets" in both Mallacoota and nearby Genoa.

"Residents are in safe locations down on the beach (in Mallacoota) and are being looked after," he told ABC Gippsland.

Image: More than 100 bushfires are burning in New South Wales, Australia's most populous state

Victoria's fire authorities said 43 structures, some of them homes, had been destroyed in East Gippsland, where more than 200,000 hectares of land are burning and eight fires are at an emergency level.

In Corryong, a town in Victoria's north, the situation was improving after a wind change, although fires were still burning on Tuesday afternoon.

A number of other towns are affected and Mr Andrews has called for help from the military and for more firefighters from the US and Canada.

My fam n I just ran for our lives through bush. Huge bushfire trapping the 5 of us in the holiday house we’re staying at. We don’t know what’s left but so grateful for the @NSWRFS 🙏 heading home to Sydney in shock. #tarbuckbay #NSWfires The #RFS are heroes!! pic.twitter.com/0ZudpxY7Ak — TraceyCorbinMatchett (@traceycm74) December 30, 2019

More than 200 fires have started in the state since Monday and four people are unaccounted for.

While officials said those missing are not firefighters, they were unable to say which part of the state they were from.

Image: An aerial view of a bushfire in Ellerslie, New South Wales

Australia's states are all experiencing bushfires as scorching summer temperatures combine with strong winds and land that, in many places, has been in drought for months or even years.

Most of the more than 1,000 homes lost have been in New South Wales, Australia's most populous state.

NSW Police Deputy Commissioner Gary Warboys said the bodies of the two men were found in a house just west of Cobargo, a village in the southeast of the state on Tuesday.

In comments reported by the Sydney Morning Herald, he said the father and son died in a "very tragic set of circumstances".

Image: Thousands of firefighters are dealing with the crisis

He said: "They were obviously trying to do their best with the fire as it came through in the early hours of the morning.

"The other person that we are trying to get to, west of Narooma, we think that person as well was caught up, trying to defend their property in the early hours of the morning."

Image: This was the scene in the town of Sussex Inlet, New South Wales, on Tuesday

The state's main city, Sydney, is expected to see temperatures of 34C (93F) on Tuesday, with 43C (109F) likely in western suburbs.

The thick smoke that has covered the city for weeks is also likely to continue.

Image: Samuel McPaul died when his fire truck rolled over on Monday. Pics: New South Wales Rural Fire Service

Three firefighters have been killed in the fires, the latest being Samuel McPaul, 28, who died when his fire truck rolled over in strong winds at the scene of a blaze in New South Wales on Monday.

Mr McPaul had been married nearly 18 months and his wife Megan is expecting their first child in May.

The 2 firefighters killed in a vehicle accident last night are Deputy Captain Geoffrey Keaton 32yrs & Firefighter Andrew O’Dwyer 36yrs, both from Horsley Park Brigade. Our thoughts are with their family, friends & fellow brigade members. #nswrfs pic.twitter.com/p3Y8zX3hBj — NSW RFS (@NSWRFS) December 19, 2019

Firefighters Geoffrey Keaton, 32, and Andrew O'Dwyer, 36, were killed earlier in December when their fire truck hit a tree and rolled over just south of Sydney.

Across Australia more than four million hectares have been destroyed, with some fire fronts stretching more than 600 miles, putting pressure on firefighters, many of whom are volunteers and have been battling the flames for many weeks.