Unknown gunmen have torched at least ten NATO oil tankers in Pakistan''s southern province of Sindh, injuring three people. The incident occurred in the wee hours of Monday in the town of Khairpur, some 350 kilometers northeast of the southern port city of Karachi, as the tankers were on their way from Karachi to Peshawar in northwestern Pakistan. The gunmen opened fire on the convoy when the drivers and the accompanying crew were having tea at a roadside restaurant. "Two drivers and a member of the restaurant staff were wounded and 10 NATO oil tankers were burnt when about two dozen armed gunmen opened fire at them," local police official Mohammad Hashim said. A nearby hotel and three shops were also engulfed in the flames. Six fire brigades were immediately dispatched to the site of the attack to put off the fire, the police said. No group has yet claimed responsibility for the Monday attack.