Dozens of pilot whales beached Saturday morning near the storm-lashed tip of South Africa, prompting a large rescue attempt. (Schalk van Zuydam/Associated Press) Marine scientists on Saturday began to euthanize 34 pilot whales that beached themselves at the southern tip of South Africa, local media reported.

Rescuers managed to push 20 whales back into the water along Kommetjie Beach near Cape Town, said Craig Lambinon, spokesman for the National Sea Rescue Institute.

But high waves washed some of them back to shore shortly after bulldozers pushed them into the water, he said.

It is unclear how the mammals became stranded in the first place.

Lambinon said the number of whales that had to be killed was not yet confirmed.

The sea rescue institution urged members of the public to clear out of the area. Curious onlookers were blocking roads leading to the beach, Lambinon said.

With files from The Associated Press