Gunmen have opened fire on passenger vehicles carrying Shiite Muslim civilians in north-west Pakistan on Thursday, killing at least 42 and wounding 20 others in one of the deadliest such attacks in recent years.

The attack happened in Kurram, a district in the north-western Khyber Pakhtunkhwa province where sectarian clashes between majority Sunni Muslims and minority Shiites have killed dozens of people in recent months.

The latest violence came a week after authorities reopened a key highway in the region after keeping it closed for weeks following deadly clashes.

Local police official Nusrat Hussain said several vehicles carrying passengers were traveling in a convoy from the city of Parachinar to Peshawar, the capital of Khyber Pakhtunkhwa, when gunmen opened fire.

Pakistan Violence
A victim is treated at a hospital in Parachinar (Dilawar Hussain/AP)

He said the dead included six women, and at least 10 passengers were in a critical condition in hospital.

Pakistan’s President Asif Ali Zardari condemned the attack and offered his condolences to the families of the victims. He also ordered authorities to take action against those who orchestrated the attack.

Shiite Muslims make up about 15% of the 240 million population of Sunni-majority Pakistan, which has a history of sectarian animosity between the two communities.

Tensions have existed for decades in some areas, especially in parts of Kurram, where Shiites dominate.

Nearly 50 people were killed in July when clashes between Suni and Shiites erupted in Kurram.

Pakistan is also carrying out intelligence-based operations in a separate conflict in Balochistan province, where militants and separatists often target police, troops and civilians, and violence has been blamed on the Pakistani Taliban and an outlawed Baloch Liberation Army or BLA group.