“Three people have been killed and 16 were injured in the attack,” Naseeb-Ullah, provincial home secretary told AFP by telephone.
“We have imposed an emergency in the hospitals while the seriously injured have been taken to Quetta’s main hospital,” he added.
Police said about two dozens attackers fired on the train when it reached Mach, which lies deep in the mountains.
A railway official confirmed the incident.
One Intelligence official in Quetta blamed the attack on Baloch militants who are fighting for more political rights and a greater share of profits from the region’s natural resources.
Hundreds of people have died in violence in the province since the insurgency flared in late 2004. Despite having some of the lowest living standards in Pakistan, the region has the richest supply of natural resources.