The two rival groups hurled low-intensity bombs at each other during the election to the managing committee of the Banonagar High School at Ousgram near Guskara, the sources said.
When the police rushed to the spot to bring the situation under control, they were also attacked in which five policemen including the SDPO Kazi Mohammed Hussain were injured, they said.
Six persons have been detained in this connection, the sources said, adding senior police officers have rushed to the spot with reinforcements.