Conservationists believe hundreds of koalas may have died this week as a massive wildfire moved through Australia's eastern coast. The fire started over the weekend in a forest in New South Wales and has since burnt down close to 5,000 acres, according to the Associated Press.

Two-thirds of the area ravaged by flames was considered a koala "hot spot," where a high number of koalas breed, the Port Macquarie Koala Hospital said. Rescuers hope to begin searching the habitat for survivors on Thursday, when the area is safe.

"If we look at a 50% survival rate, that's around about 350 koalas and that's absolutely devastating," hospital President Sue Ashton told AP of the death toll.

Get Breaking News Delivered to Your Inbox

"We're hoping it's not as bad as that, but because of the intensity of the fire and the way koalas behave during fire, we're not holding out too much hope," she said.

Update on fires. So far over two thirds of the current footprint of the fire is prime koala habitat (or was). ... Posted by Koala Hospital Port Macquarie on Tuesday, October 29, 2019

The out-of-control bushfire reportedly started following a lightning strike near Port Macquarie. The area currently remains off-limits due to the intensity of the blaze.

According to the Australian Koala Foundation, as few as 43,000 koalas are left in the wild in Australia, and their numbers continue to decline. There is not currently any legislation in any part of the country that protects the marsupials or their habitats.

Koalas are listed as "vulnerable" under the Environmental Protection and Biodiversity Conservation Act. Their survival is being majorly threatened by habitat destruction, cars and dogs, diseases and bushfires, AFK said.

Typically, many koalas have been able to survive bushfires by climbing to the tops of trees and curling into a ball. But if a fire is not contained, it can wipe out entire colonies.

It may take decades to recover the population lost in the fire.

"I think this is just a national tragedy that we potentially have lost an enormous population of animals in the past 24 hours," hospital clinical director Cheyne Flanagan told the Australian Broadcast Network. "Twenty years worth of work at the place. I just feel like walking away, I really do, I'm not going to, but it's just awful."