A mortar blast tore through a market north of Baghdad, killing eight civilians and deepening the woes of U.S. forces trying to maintain order five months after the ouster of Saddam Hussein. Amid the continuing violence, the United Nations announced it was cutting its staff in Baghdad and Iraqis prepared to bury an assassinated member of Iraq's Governing Council. The blast occurred about 9 p.m. Thursday at a market in Baqouba, about 30 miles north of Baghdad. Eight civilians died and another 18 were wounded, the Army said. Troops of the U.S. 4th Infantry Division rushed to the scene to help.