QUETTA-Two girls were killed and two others injured when a bomb exploded in their house in Nasirabad district on Friday, police said. According to details, armed persons had planted an explosive device with the wall of a house, owned by Panhal Khan in Tambo Tehsil of Nasirabad district in the limits of Khan Kot police station. The explosive device went off with a huge explosion, resulting in death of two children on the spot and injuring two others. The girls were between 6 to 8 years old. Soon after the incident, law enforcement agencies rushed to the blast site and cordoned off the area. The injured were rushed to the hospital for medical aid. According to officials sources, attackers wanted to target the members of the house, however, they had left before the bomb blast. The blast sent a wave of panic and fear across the area. Police has registered a case against unknown miscreants and started investigation. Nobody has so far claimed responsibility for the bomb blast.