Seven of the injured have been hospitalised after the explosion, which took place at 3.55 a.m. on the Sealdah-Krishnanagar local of Eastern Railway between Titagarh and Barrackpore station.
A railway spokesman told IANS the low intensity bomb blast took place following an altercation and scuffle between anti-social who had boarded the train.
Two trains were cancelled as train movement was hit following the incident.