District detective police said three people were detained in an operation near the Baghopara riverbank in Bogura on Saturday night.
Police said the operation took place in a wooded area beside the river at about 10pm.
The district detective police said they recovered a revolver, locally made weapons, yaba tablets, cash and several mobile phones.
Two adult detainees were identified by police as Rocky and Rakib.
Police did not disclose the identity of the third detainee because the person is a minor.
The detective police officer alleged that Rocky led a group and that Rakib held a second-ranking role.
The officer also alleged that the two had multiple cases involving robbery, weapons and drugs.
Police alleged that a group of five to six people had set up a tented hideout in the secluded area.
Police said their preliminary inquiry indicated the group was involved in drug trading and alleged abduction for ransom.
Police said legal action against the detainees was under way and that efforts to find others were continuing.