SYDNEY, AUSTRALIA -- Fire-ravaged Australia has launched a major operation to reach thousands of people stranded in seaside towns after deadly bushfires ripped through popular tourist areas on New Year's Eve.

Navy ships and military aircraft were deployed alongside emergency crews Wednesday to provide humanitarian relief and assess the damage from one of the worst days yet in Australia's months-long bushfire crisis.

Three people have died and five others remain missing after the country's southeast was devastated by out-of-control blazes, while at least two schools and dozens of homes were feared destroyed.

Information was trickling out of coastal communities where thousands of holidaymakers and locals were thought to have seen in the New Year taking refuge from flames at surf clubs, as power outages and damage to telecommunications towers brought down phone lines and the internet.

New South Wales (NSW) Rural Fire Service commissioner Shane Fitzsimmons said emergency services faced a "real challenge" trying to help injured people -- some reportedly suffering burns -- in isolated areas.

"We haven't been able to get access via roads or via aircraft. It's been... too dangerous and we simply can't access, nor can the people in these areas get out," he said.

'Ember attacks'

But there was cheers and relief in the town of Mallacoota -- where towering columns of smoke turned the sky pitch black and nearby fires caused waves of "ember attacks" -- after around 4,000 people who had huddled on the foreshore ringed by fire trucks survived unharmed.

"I understand there was a standing ovation at the end of that for the firefighters," Victoria Emergency Management commissioner Andrew Crisp told public broadcaster ABC.

Cooler temperatures and lighter winds also provided a window of opportunity for relief efforts Wednesday, but there were concerns over new fires sparked late Tuesday in alpine regions.

There's a lot of people holidaying, again, up in those areas," Crisp said. "We'll be prioritising those and hitting them as hard as we can. We don't need any new fires."

Firefighters were racing to take advantage of the mild weather to contain dozens of blazes, as authorities warned the fire danger would spike again on Saturday.

"At the very least, weather conditions will be at least as bad as what they were yesterday," NSW Premier Gladys Berejiklian said.

This season's blazes have killed 13 people, destroyed more than 1,000 homes and scorched about 5.5 million hectares (13.5 million acres) -- an area bigger than Denmark or the Netherlands.

The unprecedented crisis has sparked street protests calling on the government to immediately act on climate change, which scientists say is creating a longer and more intense bushfire season.

Conservative Prime Minister Scott Morrison has come under increasing pressure for his response, which has included holidaying in Hawaii as the disaster unfolded and reiterating his steadfast support for Australia's lucrative coal mining industry.