At least ten NATO oil tankers were torched here in Khairpur on Monday morning while on their way from Karachi to Peshawar, police said. According to the details, the incident took place when unknown gunmen opened fire at a NATO supply convoy moving from of Karachi to Peshawar. According to the eyewitness, the tankers were attacked when the drivers and crew were having tea at a roadside restaurant. Following the attack, the oil tankers caught fire and four people including three drivers were seriously injured. One hotel and three shops nearby the attack site also caught fire, said police. After the incident, fire brigades were called in to put off the fire. Police started the investigation of the incident.