QUETTA (APP) - Unidentified armed men on Saturday opened indiscriminate firing at a convoy of Nato oil tankers, causing damage to two of the vehicles here at Gogorat Grinala area near Machh some 25 south- east of Quetta. According to details, a convoy carrying oil for NATO coalition force, stationed in Afghanistan, were on way from Karachi via Balochistan when unknown armed assailants riding a motorbike sprayed them with volley of bullets in Machh area and fled from the scene. As a result the tyres of two of the tankers burst instantly, causing loss as hundreds of litres of oil spilled over the ground. However, no life was lost. Soon after the incident personnel of law enforcement agencies rushed to the site and cordoned off the area. A case has been registered against unidentified persons and further investigation is underway.