At least four persons were killed and several others injured in fresh spate of target killing in different areas of the city on Wednesday. Police said that unknown gunmen opened fire at a passenger bus in Quaidabad Landhi area injuring three persons. The injured were rushed to hospital where one person succumbed to his wounds. In Banaras colony, one person whose identity has not been confirmed was killed in firing by unknown armed assailants. The body was shifted to hospital for postmortem. According to SSP District Central Asim Qaim Khani bullet riddled dead bodies of two persons were recovered from Federal B Area. Hands and limbs of the deceased were tied with ropes. The bodies were shifted to Abbasi Shaheed Hospital for postmortem. The police, Rangers and other law enforcing agencies in order to maintain law and order in the city, conducted search operation and raids in Usmanabad, Garden, Lines Areas, Ranchor Line and other localities of the city during which 15 suspects were arrested. Heavy weaponary including two anti-aircraft guns, 18 Kalashnikovs, 22 pistols and 11 repeaters were recovered from the possession of detainees.