HILLA, Iraq - Unidentified gunmen killed a police officer along with four members of his family inside their home in the southern Iraqi city of Hilla late on Sunday, police and medics said.The attackers, who were driving a private vehicle, broke into the officer's house in the evening, holding him and his mother, wife and two children in one room before shooting them dead, a military source said.Military personnel, police and their families are prime targets for Sunni insurgent groups including al-Qaida's Iraqi wing, the Islamic State of Iraq, which see them as tools to support the Shi'ite-led government in its war against them.