The incident took place on Saturday morning.
Saudh Miah, 50, Fatema Begum, 40, and Abdul Alim, 25, were admitted to Dhaka Medical College Hospital (DMCH). However, their condition could not be confirmed immediately.
DMCH outpost SI Bachchu Miah confirmed the matter to the Dhaka Tribune, saying one Hamidur set a dredge pipe through Saudh's land.
When Saudh protested the action, Hamidur shot at him and his family members with a shotgun, he added.
Later, police detained Hamidur, and are investigating the incident.