According to district SP Kunal Agarwal, Khondakar Saidullah, his wife Jyostna Begum and their child were travelling in a car when they were intercepted by the police at Rasulpur.
As there was no seat belt attached in the car, the policemen demanded money and subsequently roughed up the passengers in the car.
The officer-in-charge of traffic of the area rushed to the spot and started investigation.
The police constable who intercepted the car and allegedly demanded money has been closed, Agarwal said.
Further investigation is on.