(CNN)Four whales stranded themselves on a South Carolina beach, before one of them died and three were euthanized, a local news station reported.
The four whales were discovered early Saturday morning on Edisto Beach and it wasn't clear how long they had been there, Lowcountry Marine Mammal Network Director Lauren Rust told CNN affiliate WCSC.
"Pilot whales are normally found at least 100 miles or more offshore," Rust told the affiliate. "So when you see them come this close to shore, it's definitely alarming."
The nonprofit said on its Facebook page there was a reason the whales weren't pushed back into the ocean while they were alive.
"For a deep water species like this, or any marine mammal, to be weak enough to strand, there is typically a reason (illness, injury, etc.)," the network said. "Pushing them back into the ocean is only prolonging their suffering and making them vulnerable to prey."
The network said the "more humane thing" was to end their suffering through euthanasia.
Taking them to rehab wasn't an option, as animals of this size aren't good candidates, the network said, and transporting them to a facility such as Seaworld would put enormous stress on them.
"This is all taken into account when animals strand alive," the network said. "With the help of a local vet, it was determined the animals were not healthy enough for any of these scenarios. We did our best in keeping the animals as comfortable as we could until the vet arrived."
Preliminary necropsy findings didn't show "any obvious signs to cause the mass stranding," the network said, such as an illness or human causes.
But if the whales have come far enough to strand themselves, it's most likely they'll strand again, Rust told the affiliate.
Last week, Georgia saw its second mass stranding of whales this year, according to the Georgia Department of Natural Resources.
About 26 whales beached on or near St. Catherines Island, south of Savannah, and 16 of them died. Necropsies are being performed to determine why the whales ended up on the beach.