The Detective Branch (DB) of police has found a weapons factory at Siddhirganj of Narayanganj during a drive on Friday night.
Three men were arrested during the drive, said a district Police Super office press release on Saturday afternoon.
Police also recovered a 7.65 bore foreign pistol, a magazine, two bullets and various arms-making equipment.
The arrested are Ali Akbar Lavlu Sarker, 53, his son Kamruzzaman Nawshad Sarker, 29, and Mozibor Rahman, 38.
According to the press release, police detained two riders of a motorcycle - Kamruzzaman and Mozibur Rahman - at a check post in Siddhirganj Pool area on Friday afternoon.
Police recovered the pistol, magazine and bullets while searching the body of Kamruzzaman.
Later, on Kamruzzaman's statement, they recovered a magazine and arms-making equipment from the roof of a two-storey building in Silo Gate area.
The arrested were involved in terrorist activities including selling and buying weapons in different areas, the release said adding a case has been lodged under arms act with Siddhirganj police station.