Islamabad, Nov 1 (Reporter) Four people, including three schoolchildren and a policeman, were killed and 15 others injured when a bomb went off in Pakistan's southwest Balochistan province on Friday morning, official sources said. The incident happened in Mastung district of the province, where a police vehicle was targeted by a bomb explosion, the sources told Xinhua on condition of anonymity. "The primary target of the terrorists was the police vehicle, but as the explosion happened near a school, a school van that was passing by the police vehicle also got hit by the bomb," the sources added. The injured people, including policemen and schoolchildren, were shifted to a nearby hospital. Several vehicles, including the police vehicle and school van, were damaged in the attack. No group has claimed responsibility for the attack yet...////...