Three youths were arrested with a one-shooter gun and two live bullets from a student hostel near the bus terminal area in Jhenaidah on Saturday evening.
The arrestees were identified as Faisal, Antor and Abdul Hai.
District Detective Branch (DB) police conducted the raid following a tip-off, police said.
Police said the three had allegedly been operating a drug syndicate in the area for a long time.
Antor’s father is a sub-inspector, while Faisal, described as the main accused, is a resident of Chuadanga.
Officer-in-Charge of Jhenaidah Sadar Police Station Asaduzzaman said preliminary investigation suggested that they had rented the room to store illegal firearms and operate a drug syndicate.
Police were preparing to file cases against the three under the Arms and Narcotics Control Acts.
The OC said no one involved in criminal activities would be spared regardless of their identity or connections, and strict legal action would be taken.
Police will also seek remand for questioning the accused through the court, he added.