Australia readied naval vessels and military helicopters to aid firefighting and evacuations Tuesday as thousands of people swarmed to beaches on the country's east coast.
The Australian government also called for military support and assistance from US and Canadian fire crews.
Authorities confirmed two people died overnight, raising the death toll to 11 in wildfires since the beginning of October.
The huge bushfires have destroyed more than 10 million acres, with new blazes sparked into life almost daily by extremely hot and windy conditions in bushland left tinder dry after a three-year drought.
Fueled by searing temperatures and high winds, more than 200 fires are now burning across the southeastern states of New South Wales and Victoria, threatening several towns and snapping their power, mobile and internet links.
"This is absolutely one of the worst fire seasons we've seen," Shane Fitzsimmons, commissioner of the New South Wales Rural Fire Service, told a briefing in Sydney.
"It's going to be a very long, difficult dangerous night still ahead. It's going to be another difficult day again tomorrow."
Authorities said the main firefront was moving up the coast and warned those in its path to seek shelter close to the beach.
About 4,000 people in the town of Mallacoota in Victoria headed to the waterfront after the main road was cut off. Those who could not make it there scrambled for shelter in a gymnasium and other public buildings, as emergency sirens wailed.
Some of those trapped in the town posted images of blood-red, smoke-filled skies on social media. One beachfront photograph showed people lying shoulder-to-shoulder on the sand, some wearing gas masks.
Jonty Smith via Reuters
It looked "a lot like Armageddon," said David Jeffrey, the owner of the Wave Oasis guesthouse, adding, "It's terrifying."
Fisherman Steve Casement said he had lost his house in Mallacoota to the fires.
"We are stuck here now," he told Reuters by telephone. "Everyone is pretty shocked at the moment, most of my mates are in the same position.
"Right now, I am on a trailer watching the town burn down, listening to gas bottles explode at some poor bugger's home and seeing smoke all around me."
Authorities said that by late afternoon the worst danger had passed.
Darkness in the afternoon
Several hundreds of miles north, the Jervis Bay tourist spot famed for having the whitest sand beach in the world, was shrouded in darkness in the afternoon as massive fires burned, with conditions expected to worsen.
The blazes were also generating their own weather patterns, with erratic winds, dry lightning and a significantly faster spread in different direction, fire authorities said.
Ellie Morello took refuge at a beachside motel with her mother, some neighbors, friends at pets as fires approached Batemans Bay, a town on the New South Wales coast.
"My throat's hurting from the smoke," she told Reuters by telephone. "Burned leaves and sparks were falling on me like rain."
Another small fire was closing in behind her as she spoke, she added.
"Helicopters are flying right overhead and dropping ocean waters a couple of hundred meters from where I am. But we have nowhere to go so we are still here."
Morello and others said they had run out of food and were unable to replenish supplies as shops had shut.
James Findlay, a Melbourne-based broadcaster, said his parents' home in the town was gutted after palm trees on the lawn caught fire. The couple were vacationing in New Zealand.
"There were a lot of family heirlooms in there," he told Reuters. "A lot of priceless memories."
The fires have been spread across four states, with fronts stretching hundreds of miles in some cases, affecting many towns and rural areas.
The two people who died overnight were believed to have been a father and son protecting their property near the town of Cobargo in New South Wales, police said, with a third missing, feared dead, while in Victoria, four more were unaccounted for.
Bushfires burned on the outskirts of Sydney, cloaking the harbor city in smoke ahead of a fireworks display planned for New Year's Eve.
By Sonali Paul and Swati Pandey/Reuters