An Austrian military guard has been killed by his superior officer in an exchange of fire. Beforehand, the soldier had fired several shots with an assault rifle at the Flugfeld Barracks located at the airfield in the city of Wiener Neustadt to the south of Vienna on Friday morning, the spokesman for the Austrian Defence Ministry, Michael Bauer, told dpa. The superior officer then shot the man with a pistol, he said. According to initial information, the incident was preceded by an argument, Bauer said. The supervisor was injured in the course of the argument. According to the spokesperson, the…