Two teens has disappeared when they went to fish with four other friends in Kottukalli Sea in Pottuvil last evening.
One of the teens had slipped and fallen into the sea and two others had jumped behind the boy in an attempt to rescue him.
However, the slipped youth and one of his rescuers were drowned, while the other had managed to save himself.
The victims are aged 14 and 17, the police say.
Residents of the area, police and the Sri Lanka Navy have launched a search for the missing boys.