The clash occurred at the Arhuakandi Government Primary School centre around 8.30am on Sunday, said Assistant Returning Officer and Harinakundu Upazila Nirbahi Officer Ashraful Amin.
RAB personnel did a baton-charge on the clashing groups to control the situation.
Balloting was suspended for an hour as voters panicked because of the clash, said Presiding Officer Hafizur Rahman.
Polling resumed around 9.30am.
