A powerful bomb was found in the heavily-guarded complex of Border Security Force (BSF) at Nongpok Sekmai area in Manipur's Thoubal district on Friday. Personnel of 88th BSF battalion found the 'lethod' bomb and called bomb experts, who later defused it, official sources said. The bomb might have been fired by militants using a rocket launcher in an attempt to attack the BSF camp, they said. In another incident three army personnel were injured when armed insurgents attacked a security patrol in Manipur's Churachandpur district, official sources said. The insurgents, hiding by the roadside, fired at an Army patrol belonging to Gorkha Rifles at Phutum Khongkhai village on Wednesday night, they said. The security personnel retaliated and the fighting continued for nearly an hour, sources said adding casualty, if any, on the side of the insurgents was not known. Though the identity of the insurgents was not know, police said it suspected that they belonged to the People's Liberation Army (PLA).