BAGHDAD, Iraq - Insurgents kept up pressure Saturday, detonating a string of bombs in Baghdad and other Iraqi cities Saturday that killed at least 15 Iraqis and one American soldier. The U.S. military announced that four other Americans had died in hostilities on Thursday.

Three roadside bombs and three suicide car bombs exploded in the space of five hours in Mosul, killing five Iraqi civilians and wounding five Iraqi soldiers, five Iraqi civilians and the U.S. soldier, the U.S. military said.

In Baghdad, a car bomb exploded outside the offices of a Sunni political group, killing three people. Police had raided the offices on Friday. The Associated Press reported five others killed by gunmen and bombers in other attacks around Baghdad.