Fast track court-IV additional judge Shahjanand Sharma passed the order convicting Munna Rai, Md Israil and Prabhu Sahni after finding them guilty in the Arms Act case.
The three would have to undergo additional imprisonment for three years if they failed to deposit the fine with the court.
The three had assembled at Chheni Chapra village in East Champaran district on January 20 to plan the killing of a person when Muzaffapur and East Champaran police raided and apprehended them and seized a AK-56 rifle, a .9mm pistol, a country-made pistol and a haul of ammunitions.
The accused were chargesheeted and put on speedy trial by a fast track court which convicted them within eight months of registration of case against them.