The incident occurred on the outskirts of Batupalli village under Kagaznagar mandal in the district when a group of four youths went for swimming in the canal at around 7 AM, they said.
"It seems out of the four students only one of them knew swimming. But, three others who did not know swimming drowned and after a four-hour operation, a rescue team retrieved their bodies," Kagaznagar Circle Inspector Ramesh Babu said.
The deceased were identified as Syed Abrar Ali (22), a BTech student, Md Abdul Aziz (17), a second-year intermediate student, and his younger brother Md Abdul Aleem (16), a first-year intermediate student, the Inspector said.