Armed men opened fire on passenger vehicles in the tribal region of Kurram in northwestern Pakistan, reported "Reuters", News.bg reports.
At least 38 people died in the attack, including a woman and a child, and another 29 were injured.
Chief Secretary of Khyber Pakhtunkhwa province, Nadeem Aslam Chaudhry, warned that the death toll was likely to rise:
"This is a great tragedy."
The convoys were traveling between the cities of Peshawar and Parachinar when they were attacked. According to local sources, tensions between the Shiite and Sunni communities in the region, which have been escalating for years over land disputes, may be the reason for the attack.
No group has so far claimed responsibility for the attack.
President Asif Ali Zardari strongly condemned what happened, and the investigation continues.