MIR ALI/BANNU: Three Frontier Constabulary (FC) troops were killed and three injured in an improvised explosive device (IED) blast on the Bannu-Mir Ali road on Wednesday, while four soldiers were killed when their army helicopter crashed into Barani Dam in Bannu. Two of the paramilitary troops died at the scene while a third later died of his injuries at Mir Ali district hospital. The team of six FC personnel was patrolling the road as an army convoy was to head for Miranshah from Bannu on the route. Sources said one of the jawans might have stepped onto the IED meant for the convoy. Three army soldiers escaped the helicopter crash unhurt. "Apparently the crash was causes by some technical fault, but the exact cause will be known after an inquiry into the incident," Shaukat Sultan, director general of Inter-Services Public Relations (ISPR), told Daily Times. Bannu DPO Mohammad Iqbal told Daily Times that there were seven soldiers on board the chopper when it left Bannu for Miranshah, the agency headquarters of North Waziristan.