Railway officials said that the Jaffer express was going to Quetta from Rawalpindi when it was hit by a bomb.
"The impact was not direct but it left at least 10 passengers injured," a spokesman for Pakistan Railways said.
Three compartments of the train derailed and the track was destroyed in the attack, causing disruption of railway traffic in the area.
The injured people were shifted to a nearby hospital.
No group has claimed responsibility for the attack yet.