A Pakistani railways official says a bomb has exploded on a passenger train in the country's southwest, killing at least three people and wounding 10.

The official, Tufail Ahmad, said the bomb went off on Friday near the village of Mach in Baluchistan province. He says the train was heading to the garrison city of Rawalpindi from Quetta, the provincial capital.

Ahmad says the casualties were taken to nearby hospitals and that some of the wounded passengers are listed as being in critical condition.

No one has claimed responsibility for the attack, but separatist groups in the province have claimed similar attacks in the past.

For over a decade, Baluchistan has been the scene of a low-intensity insurgency by ethnic Baluch separatists who want autonomy or outright independence.