At least 300 detonators were seized from New Jalpaiguri railway station on Thursday.
The detonators in three packets were found lying on the narrow gauge platform at 0830 IST, Assistant Commissioner, Railway Police Force, K K Dasgupta said.
The narrow gauge platform is the terminal point of the famous toy train to Darjeeling, which is on the world heritage list.
Senior police officials, including Deputy Superintendent of Police Asit Pal, have rushed to the spot.
No arrests have been made yet, but the police have cordoned off the area, sources said.
