At least 45 dolphins were washed ashore near Punnaikayal village in Tamil Nadu’s Tuticorin district on Monday evening. The forest department and local fishermen helped rescue and direct most of them back to the sea, but at least four dolphins had died before the effort started, The Times of India reported.

Fishermen spotted the dolphins landing on the shore around 6 pm on Monday, and immediately informed the fisheries department, The News Minute reported. Forest department officials reached the spot at 8 pm and sent the dolphins back to the sea.

Around 6 am on Tuesday, one of the dolphins that had been rescued returned to the shore, The Times of India report said. Two forest department swimmers successfully drove it back into the sea in 30 minutes. But another one was seen swimming towards the shore. It hit a rock wall and started bleeding. However, the dolphin managed to swim away.

“These dolphins are from the Indian Ocean, but we are yet to find out why they swam ashore,” S Logasundaram, a forest range officer told The News Minute. Fishermen said more dolphins could wash ashore over the next few days.

In January 2016, around 80 pilot whales had washed ashore dead at Manapad in the same district, after first being rescued.

But L Ranjith, a scientist from the Central Marine Fisheries Research Institute in Tuticorin said the chances the dolphins will return was low. “Both pilot whales and dolphins travel using electromagnetic waves,” he told the newspaper. “Pilot whales follow a pilot, and when the pilot strays, the whole heard dies. That is not the case for dolphins.”

The district forest officer of Tirunelveli, T Sampath, said a team will be stationed in Punnaikayal for a week to rescue dolphins if they wash ashore again.