U.S. and Iraqi forces clashed with militiamen in Diwaniyah early Sunday, a southern city coming under the growing influence of the Mahdi Army loyal to cleric Muqtada al-Sadr. Fighting could be seen in two neighborhoods and heavy explosions could be heard. An Associated Press reporter saw U.S. soldiers sealing off roads to the city, in an apparent attempt to keep the insurgents from being reinforcements. Fighting broke out after a joint U.S.-Iraqi unit raided the house of Kifah al-Greiti, a Mahdi Army commander in the city, Iraqi Army Capt. Fatiq Ayed said. The U.S. command in Baghdad had no immediate comment on the fighting.