PESHAWAR, Pakistan -- A Pakistani official says gunmen forced 20 Shiites off buses in northern Pakistan and killed them.

The police official said the incident happened Thursday in the Naran Valley.

The official spoke on condition of anonymity because he was worried about retribution.

The Deputy Inspector General of police in Gilgit, Ali Sher, said the victims were travelling from Rawalpindi, near the capital Islamabad, to Gilgit, a mostly Shiite area.

There have been several such sectarian attacks in the region in the past. Many Sunni extremists do not view Shiites as true Muslims.