Four pilot whales that stranded themselves on Edisto Beach, in South Carolina, are seen on September 28, 2019, in a photo taken by marine biologist Peyton Sasnett. One of the whales died and the other three were euthanized. Peyton Sasnett/WCSC

Edisto beach, South Carolina — Biologists will perform necropsies on one whale that died and three that were euthanized after becoming stranded on a South Carolina beach. Lowcountry Marine Mammal Network Director Lauren Rust told CBS News affiliate WCSC-TV that the whales were found Saturday morning on Edisto Beach, but it was not clear how long they had been there.

Marine biologist Peyton Sasnett, who went to the beach, said they appeared to be pilot whales.

Rust said pilot whales are usually at least 100 miles offshore, "so when you see them come this close to shore, it's definitely alarming."

Getting results of the necropsies could take a few week weeks. Rust said tests would determine whether the whales suffered internal injuries, a viral infection or fell ill because of human factors like consuming plastic in the ocean.

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Rust told WCSC that there were no obvious signs of physical trauma on the whales. She said trying to push the whales back out to sea would likely have failed, as whatever caused them to strand in the first place would not have been addressed.

"Nine times out of 10, they will restrand themselves," Rust said. "So you're prolonging the whale's suffering, you're prolonging the inevitable and you're putting it out there for a predator."

She said it was possible that the four whales were two mothers and their calves.

In July about 50 pilot whales beached themselves on the Georgia coast for unknown reasons. Dozens of residents took part in an impromptu effort to push them back out to sea, but at least three of the animals died.