Catastrophic bushfires in eastern Australia have killed at least three people and forced thousands from their homes, with the death toll expected to rise as firefighters struggle towards hard-to-reach communities.

In the normally picturesque coastal town of Forster -- one among dozens hit along the eastern seaboard -- vast plumes of smoke shot out from multiple blazes as water bombers swooped in overhead.

A large bushfire in the Wollemi National Park near Lithgow, west of Sydney A large bushfire in the Wollemi National Park near Lithgow, west of Sydney Photo: AFP / DAVID GRAY

And in Bobin, around 60 kilometres (35 miles) north of Forster, the whole town was scorched with some fires soaring 10 metres (30 feet) along the tree canopy.

Some homes were completely burned to the ground in the small rural town, and in one just a fireplace could be seen among the smouldering rubble.

Prime Minister Scott Morrison said that, if needed, the military could be called on to help some 1,300 firefighters who are tackling around 100 separate blazes.

Satellite image showing bushfires in Australia's New South Wales, with focus on fires in the last 24 hours Satellite image showing bushfires in Australia's New South Wales, with focus on fires in the last 24 hours Photo: AFP / Patricio ARANA

Several people are still unaccounted for and 30 more have been injured -- mostly firefighters working for hours on end in smoky, smouldering scrubland and blazing forests of towering eucalyptus.

"My only thoughts today are with those who have lost their lives and their families," Morrison said, as hundreds of civilians also volunteered to help their hard-hit neighbours.

The government says the military could be called on to help some 1,300 firefighters who are tackling around 100 blazes The government says the military could be called on to help some 1,300 firefighters who are tackling around 100 blazes Photo: AFP / SAEED KHAN

A body was found in a burnt-out building near the east-coast town of Taree, police said, while another victim was found in a car and a woman died despite medics trying for several hours to save her.

As hot and windy weather eased slightly on Saturday, the number of most serious fires fell to just a handful from an unprecedented 17 on Friday.

But within an area spanning almost 1,000 kilometres (600 miles), schools were burned and at least 150 homes were destroyed, while authorities were forced to evacuate detention centres and old people's homes.

In the normally picturesque coastal town of Forster, vast plumes of smoke shot out from multiple blazes In the normally picturesque coastal town of Forster, vast plumes of smoke shot out from multiple blazes Photo: AFP / PETER PARKS

It was a narrow escape for Don Russell, with the fire coming within meters of his home in Taree.

"They've done a top job, them fellas," Russell told AFP after a crew of six firefighters brought the blaze under control.

The catastrophic fires have forced thousands from their homes The catastrophic fires have forced thousands from their homes Photo: AFP / PETER PARKS

His next-door neighbours were not so lucky, however -- their home went up in flames Saturday afternoon. No one was home.

"It used to be God's country, but it ain't any more," said another neighbour, 72-year-old Dave Scott.

New South Wales's rural fire service said an emergency warning was in place for four fires among the dozens raging across the state.

High winds flung embers and burnt debris far ahead of the fires' front lines High winds flung embers and burnt debris far ahead of the fires' front lines Photo: AFP / PETER PARKS

A large bushfire in the Wollemi National Park near Lithgow, west of Sydney A large bushfire in the Wollemi National Park near Lithgow, west of Sydney Photo: AFP / DAVID GRAY

Bushfires are common in Australia and a vast corps of firefighters had already been tackling sporadic blazes for months in the lead-up to the southern hemisphere summer.

But this was a dramatic start to what scientists predict will be a tough fire season -- with climate change and weather cycles contributing to the dangerous combination of strong winds, high temperatures and dry conditions.

"We're experiencing tinderbox-like conditions across much of the state and all it takes is one spark to start a fire that may burn for days," said Queensland's acting fire commissioner Mike Wassing.

Meanwhile, New South Wales premier Gladys Berejiklian warned that next week's weather forecast "could mean we're not through the worst of it".

Morrison, whose government has played down the threat of climate change, sought to deflect questions about what impact it may have had.

"Australia has been battling ferocious fires for as long as Australia has been a nation, and well before. And we will continue to do so," he said.

Firefighters had described the conditions Friday as "difficult" and "dangerous". In some areas, residents were stuck and told to simply "seek shelter as it is too late to leave".

Local radio stopped normal programming and provided instructions about how to try to survive fires if trapped at home or in a vehicle.

Across the central coast, smoke billowed high into the sky and residents posted images online of tangerine skies and storeys-high trees ablaze.

Authorities said some of the fires were creating their own weather conditions -- pyrocumulus clouds that enveloped entire towns.

Despite easing conditions, a prolonged drought and high aridity levels will continue to make circumstances combustible.

Earlier this month, some of the same fires cloaked Sydney in hazardous smoke for days. On Saturday it was Brisbane's turn, with the fires enveloping the city centre in a veil of acrid fog.

Swathes of Australia have gone months without adequate rainfall, forcing farmers to truck in water, sell off livestock or leave their land to lie fallow.

Jim McLennan of La Trobe University said the bushfires were "unprecedented", coming so early in the season and in areas that usually have moist soils and vegetation.

"However, the fire situation is consistent with our new world of bushfire threat associated with climate change".

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