The US military said seven "criminals" have been killed in fighting in Baghdad's main Shiite militia stronghold of Sadr City. A statement said American soldiers responded after coming under small arms fire from militants. The military said four of the militants were killed in an airstrike and three others by an Abrams tank. Monday's announcement comes a day after US and Iraqi troops killed 38 militants in the fiercest fighting in weeks. The clashes followed a government crackdown against Shi'ite militias led by radical cleric Muqtada al-Sadr's Mahdi Army.