Another woman, who was critically injured in the incident, said Bangra Bazar Police Station Officer-in-Charge (OC) Mahfuzur Rahman.
The deceased were identified as Ruby Akter, her son Russell, and daughter Jonaki. The injured woman, Ruma, has been hospitalised in critical condition.
Locals said that the deceased, Ruby, and his family members were involved in drug dealing and robberies by establishing a reign of terror in the area, reports UNB.
The OC said local residents also attacked their house, killing three people and seriously injuring one.
There are multiple cases against the deceased in Muradnagar, Nabinagar and Bangra Bazar police stations, he added.