Islamabad, March 4 (RHC)-- Pakistani officials say gunmen have opened fire on a NATO supply convoy in the country’s northwest. Local administration officials said the convoy of four vehicles came under fire on Tuesday in the tribal Jamrud region, located 40 kilometers northwest of the city of Peshawar.

The vehicles were transporting supplies to U.S.-led NATO forces in neighboring Afghanistan. The four containers were reportedly on their way to Afghanistan when four gunmen riding two motorbikes opened fire at them in Jamrud, killing two helpers and wounding one driver and one helper. The gunmen reportedly fled from the scene and no group has claimed responsibility for the incident.

The attack comes less than a week after the ruling party in Pakistan’s northwest ended a three-month blockade of NATO supply route to Afghanistan. The Pakistan Tehreek-e-Insaf party had blocked the vital supply line in protest at U.S. drone strikes, which have claimed thousands of lives on Pakistani soil.

The slaughter of Pakistani people, including women and children, in U.S. drone strikes has strained relations between Islamabad and Washington, and Pakistani officials have complained to the U.S. administration on numerous occasions.