The incident occurred as the coupling of one of the waggons of the goods train snapped, following which there was a sudden jerk.
The labourers, who were to unload the cargo, were sitting on the rails. The jerk toppled them to ground and they were trapped under the heavy rails which fell off, said Sagar GRP Police Station In-charge L S Kashyap.
Dallu Ahirwar (55), Manoj Ahirwar (26), Harinarayan Ahirwar (30) and Damodar Ahirwar (22) were killed, he said.