--STORY CONTAINS GRAPHIC IMAGES --<br/> <br />Blood spills in Iraq after gunmen killed at least five policemen in an attack on a police checkpoint south of the Iraqi city of Kirkuk.<br/> <br />The pre-dawn attack took place in Taza, a predominantly Shi'ite town.<br/> <br />Authorities say the gunmen first slit the throat of a policeman on duty on the night shift. Later they entered another building where four other policemen were sleeping. They shot them dead on the spot.<br/> <br />No one is immediately claiming responsibility for the attacks.<br/> <br />Kirkuk sits atop one of Iraq's key oil producing fields. It is an ethnically mixed city at the heart of a dispute between the Arab-led central government in Baghdad and ethnic Kurds who have regional authority.
