More attacks
In a separate incident during the day, at least eight people were killed when a suicide bomber rammed his explosives-laden car into a checkpoint manned by Iraqi soldiers and a local group.
Colonel Mohammed Khalid, the local police officer said: "The suicide attack took place in Dhuluiya, 70 km from north of Baghdad, in Salaheddin province, at around 3:15pm (1215 GMT)."
US bases are now located inside Iraqi neighbourhood and more US soldiers are getting out of their armoured vehicles to patrol Baghdad on foot, as a part of the military's strategy.
While the face-to-face contact builds goodwill, it also gives suicide bombers, who slip by vehicle security checkpoints simply by walking, a better access to striking soldiers.