They are Chandan Sarkar, 36, his daughter Kiron Sarkar, 6, and his nephew Apurba Sarkar, 5, of the village.
Quoting locals, officer-in-charge of Sherpur Police Station Humayun Kabir said Chandan went to the river for fishing along with his daughter and nephew.
When he was swimming in the river carrying both the children on his shoulders all three drowned.
Local divers found bodies of Chandan and his daughter while his nephew remained missing.
Divers from Rajshahi fire service were sent to the spot to trace the missing child, said Sherpur Fire Service Station Officer Ratan Hossain.