<br/>Atleast seven security personnel are killed when their vehicle was hit by a landmine explosion triggered by Maoists in Orissa's Koraput district today. According to police, the van carrying jawans of the elite anti-naxalite Special Operation Group (SOG) was proceeding to clear roads obstructed by the Maoists when the landmine laid by ultras went off at Mantriamba area, about 55 km from Koraput . <br/><br/>Two more vehicles carrying security jawans following the ill fated vehicle however narrowly escaped. Injured have been admitted to hospital. Sources said, a brief exchange of fire also took place between the security personnel and the rebels near the blast site. <br/><br/>Our correspondent reports, additional forces have been dispatched to the spot for carrying out combing operation in the area.