The youth were taking a holy dip in the sea on the occasion of 'Thai Amavasai' and were caught in high tides, police said.
District Superintendent of Police, Deshmukh Shekar Sanjay said a group of youth were caught in the tides.
"The rescue teams saved a total of 10 persons and all of them were rushed to Vedaranyam government hospital.. Four persons were declared brought dead," he said.
While three are receiving treatment at Vedaranyam government hospital, two others have been referred to Tiruvarur Medical College Hospital, said the senior police official adding the search operations were on.