They were identified as Rubi Begum, 58, her son Rasel, 35, and daughter Jonaki Akter, 28, said sub-inspector Md Nahid of Bangrabazar Police Station.
The incident took place in the morning in Koraibari village of Akbapur union under Bangra police station.
Mahfuzur Rahman, officer-in-charge of the police station, said villagers alleged that the trio have long been involved in drug peddling.
