The detonators, cartridge shells and wire were found at the rented home of the three persons.
Police found 200 detonators and 230 cartridge shells and arrested three persons at Pradhan Nagar in Siliguri today.
The three were residents of Nepal and staying in Assam More area under Pradhannagar police station limits for last six months, Commissioner of Police, Siliguri, C S Lepcha said.
They were picked up following a tip-off and police were trying to ascertain why so many detonators were stockpiled at their rented accommodation.
Explosives and wires stockpiled at the home in Siliguri.
Police also seized several metres of wires from them.
The three earlier lived in neighbouring Assam's Silchar and told the sleuths they had worked in a mine there (in Silchar).
They were identified as Krishnaprasad Adhikary, 50, and a couple - Puja Limbu and Dawang Shering Bhutia, 40.