Acting on a tip off, the four, including a father-son duo, were arrested from their rented house in Seth Srilal Market in Siliguri, Police Commissioner Jag Mohan said.
The police seized Rs 11,000 in cash, three mobile phones and three SIM cards were seized from them.
The four used to take money from people claiming they were members of GJM's guerrilla wing or, sometimes, Maoist organisation, the police commissioner told a press conference.
The four are identified as Dilip Trikhatri, his son Dipesh Trikhatri, Bimal Darji and Birbahadur Gupta.