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 accomodation.
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).
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