Marine experts and government officials are racing to save hundreds of pilot whales after a mass stranding in Australia, with dozens of the animals already dead.

About 270 pilot whales are stranded in Strahan, a small town in Tasmania, an island off the southern coast of Australia. They're scattered along two sandbars and the strip of beach, according to the Tasmanian Marine Conservation Program, which is leading the rescue operation.

"Late yesterday, we had about a third of the animals were already deceased," said wildlife biologist Kris Carlyon at a news conference on Tuesday morning. He added that it was difficult to make a more specific estimate of deaths, since the whales were spread out across a large area and some locations were inaccessible.

"This is a really challenging event," he said. "In terms of mass strandings in Tasmania, this is up there among the trickiest we've ever had to deal with."

Other potential problems include the unpredictable tide that's washing in, and the possibility that the distressed whales might attract sharks to the area.

The rescue teams, numbering about 60 people, include volunteers, police, fish farms and the Tasmania Parks and Wildlife Service. With the clock ticking, they're forced to triage by starting with whales that have the best chance of success, said Carlyon.