Tezpur (Assam), May 27 (PTI): An army jawan has been been killed and six others were injured when a mortar shell exploded during field firing exercise at Tawang in Arunachal Pradesh. The incident took place on Thursday in an area bordering China, about 35 km from Tawang-Gamrala area, killing one jawan and seriously injuring six others, Defence spokesperson of Tezpur 4 Corps, Lt Col Sombit Ghosh, told PTI here today. Three of the critically injured jawans were evacuated to army s Command Hospital at Kolkata by helicopter while three others were admitted to Tezpur Army Base Hospital.