Among the fatalities in the attack, which occurred in the Kurram tribal district, were a woman and a child, Chaudhry said, adding: “It’s a major tragedy and death toll is likely to rise."
Tensions have existed for decades between armed people over a land dispute in the tribal area that borders Afghanistan.
No group claimed responsibility for the incident.
"There were two convoys of passenger vehicles, one carrying passengers from Peshawar to Parachinar and another from Parachinar to Peshawar, when armed men opened fire on them,” a local resident of Parachinar, Ziarat Hussain told Reuters by telephone, adding that his relatives were traveling from Peshawar in the convoy.
President Asif Ali Zardari, in a statement, strongly condemned the attack on passenger vehicles.