ASI Vinod Kumar said that investigators were now looking to trace those persons to whom the illegal arms had been supplied.
The arrested accused, identified as Ramesh, Radhakishan, Chetan and Sonu used to manufacture the weapons in the Mujesar and Old Friends' Colony areas.
Police sources today added that they had uncovered a total of three workshops and also found finished weapons along with incomplete ones at the lodgings of Radhakishan, Ramesh and Chetan.
Police said that Ramesh was the mastermind behind the operation and had been engaged in the activity for 12 years.