'Gruesome accident'
Laith al-Massudi at the hospital in Hilla said: "It was a gruesome accident. The body parts of the dead were brought to the hospital yesterday. All the 13 members were killed instantly."
Police are searching for the train driver.
Iraq's 2,300km operational rail network has been reduced by more than half since economic sanctions from 1991 Gulf war and the 2003 invasion by US-led forces.