At least two people were killed and as many injured in an attack by armed militants targeting four vehicles carrying NATO supplies for Afghanistan in northwestern Khyber tribal agency on Tuesday, said officials. According to security officials, the vehicles came under attack in Jamrud area of Khyber Agency as they were on their way to neighboring Afghanistan. A senior local administration official, Jehangir Azam Wazir said that the four containers were 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 security forces immediately reached the site of the incident and a search operation went underway but the culprits managed to escape the scene unhurt.No group has admitted responsibility of the attack as it came just three days after Tehreek e Taliban Pakistan (TTP) announced a month long ceasefire to resume peace talks with Pakistani government.Pakistan is a major transit supply route for the NATO troops in landlocked Afghanistan and Khyber Agency, one of seven districts that make up Pakistan's semi-autonomous tribal belt, is one of the shortest and main route used to carry supplies.