Three people, including two women, were beaten to death by a mob on suspicion of drug dealing in the Kharibari area of Muradnagar upazila in Comilla early on Thursday.
Another woman was critically injured in the incident, said Bangara Bazar police station Officer-in-Charge (OC) Mahfuzur Rahman.
The deceased were identified as Ruby Akter, her son Rasel, and daughter Jonaki.
The injured woman, Ruma, has been hospitalized in critical condition.
Locals said that the deceased Ruby and her family members were involved in drug dealing and robberies through establishing a reign of terror in the area.
The OC said local residents also attacked their house.
There are multiple cases against the deceased at Muradnagar, Nabinagar and Bangara Bazar police stations, he added.