Angry with frequent disruptions in power supply in southern parts of Gopiganj for the past one month, residents marched to the local power department office and locked the gates after chasing away staff members, according to police.
Later, the protesters staged a dharna on the highway.
When police team used mild force to disperse the crowd, the protesters indulged in brick-batting injuring six policemen, including two sub-inspectors, police sources said.
The protesters also damaged window panes of several vehicles, which had piled up on the highway, they said.