PESHAWAR: Unknown armed men attacked a bus in the Kurram tribal region on Tuesday injuring at least three passengers.

The region's political administration said the bus, which was heading from Parachinar towards Peshawar and was carrying 20 passengers, was attacked with rockets and automatic weapons.

The injured passengers were shifted to Combined Military Hospital (CMH) Tull for treatment, whereas, security forces had surrounded the area and had started a search operation.

Kurram is one of the seven Pashtun tribal regions in Pakistan on the Afghan border, an area widely considered the headquarters of Al Qaeda militants and their allies.

Kurram, the only part of Pakistan’s border region that has a significant Shia population, has been racked by sectarian violence between Sunni and Shia tribes.