The three youths, Babu Das, Hirol Hazra and Shibshankar Chowdhury noticed the crack in the line when the express was approaching at which they signalled it to stop, Burdwan Station Master Ashim Kumar Adhikary said.
The driver of the train, Apurba Kuamr Banerjee, applied the brakes, but the engine crossed the crack before coming to a stop, while a parcel van which was just behind got stuck, Banerjee said.
The train was later brought at slow speed to the Burdwan station. It later left for its destination.
The track was repaired while train services were suspended for some time.