A cocktail explosion took place at a madrasa in Meherpur on Friday night.
Six BNP leaders and activists were arrested on suspicion of being involved in the incident.
Officer-in-Charge (OC) Abdur Razzak said that BNP-Jamaat leaders and activists were holding a secret meeting in a madrasa. When a police team reached the spot, two cocktails exploded.
Later five cocktails, two local weapons and batons were seized from the spot.
The police officer said that the process of filing a case is ongoing.