South African rescue teams have managed to return to the water 20 false killer whales which beached near Cape Town but others have had to be put down.
Bulldozers were used to try to push the 55 adults and calves back into the water as high winds and waves hampered the rescue operation.
The whales, about 3m (10ft) long, are common to the waters off South Africa.
It is unclear how the mammals became stranded and some which were returned to the water swam back to the beach.
Craig Lambinon, a spokesman for the National Sea Rescue Institute, told Reuters news agency that he could not say how many whales would have to be killed.
Those who could not be saved were being shot humanely in the head.
It was the first mass beaching of whales Mr Lambinon had seen on the popular beach at Kommetjie, near Cape Point.
"As soon as we put them back into the sea, they swim back to the beach again," he said earlier.
The NSRI initially identified them as pilot whales, but said later they were false killer whales, Reuters reports.
Rough seas also pushed some whales back ashore.
Volunteer helpers and onlookers flocked to the area, blocking the main approach road, reports say.
It was a sad situation, we tried to move them towards the sea, they would go and we would be all cheering and then they would come back towards the beach again. The sea was rough which made the whole process even more tiring for everyone. We tried to calm them down and they did as soon as we touched them, they looked at us with their incredible eyes as if to say 'what is happening to us?' There was nothing we could do. The volunteers really tried hard. It was very sad indeed. Celine, Kommetjie
As a volunteer on the scene, I am deeply impressed by the goodwill of local residents who pitched in to help. Still, I feel that we could have done better. Although most whales washed up on the beach, there were many washing up on the rocks to the south of the beach. There seemed to be little communication or co-ordination between the various teams tending to the whales - especially in the late afternoon. Volunteer civilians risked themselves in rocky, rough waters with little assistance or direction from the NSRI or other experts. Confusion reigned as to the best course of action. In addition, the public were told to stay away completely, yet volunteers were exhausted and in need of replacement volunteers in the water. When the shooting began, a wave of panic and sadness swept the crowd. It seems a tragedy of epic scale to work for hours on end, only to have the whales return to shore and be shot. We'd all love to know what drove them out of the water. We're all left wondering - is man(un)kind responsible? Candice Pelser, Cape Town South Africa
This page is best viewed in an up-to-date web browser with style sheets (CSS) enabled. While you will be able to view the content of this page in your current browser, you will not be able to get the full visual experience. Please consider upgrading your browser software or enabling style sheets (CSS) if you are able to do so.