Six suspects were arrested on Monday in the Jamalpur area of West Bengal's Burdwan District and a car with a Ministry of Defence (MoD) license plate in which they were travelling was impounded.
The Swift Dzire car also had a Ordinance Factory Board sticker.
The persons detained have been identified as Sakir Ahmed, Salim Akhtar, Sheikh Irfan, Sheikh Ansaruddin, Abdul Akhtar and Sheikh Shahrukh.
Police said that they failed to provide any identification to support their claim that they were defence ministry employees, nor did they have valid vehicle documents.
The suspects are being interrogated by the police, but so far, no information has been gleaned.
They are in police custody and would be produced in a lower court later in the day.