
The incident occurred in the South Kadamtali Kashempara area near Burma Stand.
The deceased were identified as Md Rasheduzzaman, 22, his brother-in-law Md Galib, 18, and his sister-in-law Mosammat Suraiya, 12.
Rasheduzzaman hailed from Monag village under Kashiani upazila in Gopalganj district and was the son of Delwar.
Galib and Suraiya were from Raghunathpur village under Kalia upazila and were children of Akram.
According to police and locals, Rasheduzzaman, Galib and Suraiya entered the DND Lake for a bath between 3:30pm and 4:00pm. At one point, they went underwater and failed to resurface.
When they could not be found, locals informed the Fire Service and police.
On information, divers from Narayanganj River Fire Station rushed to the scene and launched a rescue operation. After several hours of search, they recovered the bodies, reports UNB.
Mizanur Rahman, Inspector (Investigation) of Siddhirganj Police Station, said family members stated that all three victims knew how to swim.
Police are investigating how the accident occurred despite their swimming ability.
Police said the bodies would be handed over to the families after completion of legal formalities.