A railway official said no passenger of the Peshawar-bound train, which runs between Karachi and Peshawar, was injured in the incident.
He said the track had been restored for the down line traffic.
It is learnt that the train driver knew it only after reaching Sama Satta that eight coaches of the train were missing.
The official said rescue trains were dispatched immediately from Khanewal, Rohri and Sama Satta to clear the track.
After the incident, several trains were halted at various railway stations. Only Shalimar Express, Down 28, had been allowed to leave for its destination from Bahawalpur till the filing of this report at about midnight.