PERTH — Wildlife authorities confirmed that 28 long-finned pilot whales died and more than 100 others returned to the ocean after they were found stranded at a Western Australian beach on Thursday.

Earlier in the morning, four pods of up to 160 pilot whales in total were beached at Toby's Inlet near Dunsborough, spreading across about 500 meters.

A team of experienced staff was in the final stage of removing the dead whales from the beach. Samples and data were also collected from the marine mammals to help scientists understand their behaviors

At around 4:45 pm local time, the Western Australia Department of Biodiversity, Conservation and Attractions (DBCA) said in its latest update that 28 of those stranded whales lost their lives, while the others moved further offshore and traveled north.

READ MORE: 51 stranded whales die overnight in Western Australia

Vessels and a spotter plane have been deployed to track down the pod that swam out to sea.

"We haven't seen them. We are hoping they've gone out nice and deep and that they won't re-strand again. Not seeing them is a good sign. That means they're not in the shallows ... but the spotter plane will go up again tomorrow and hopefully, we won't see the pilot whales again," said DBCA Regional Wildlife Officer Pia Courtis.

A team of experienced staff was in the final stage of removing the dead whales from the beach. Samples and data were also collected from the marine mammals to help scientists understand their behaviors.

READ MORE: Nearly 100 whales die after mass stranding in New Zealand

According to DBCA Senior Research Scientist Marine Fauna Holly Raudino, most of the 160 pilot whales are female adults with a few calves, and the cause of the mass stranding currently remains unknown.