U.S. warplanes pounded the vast Baghdad slum of Sadr City overnight after an American patrol came under small arms fire, the military said Tuesday. Hospital officials said at least one person was killed in skirmishes between U.S. troops and fighters loyal to renegade Shiite Muslim cleric Muqtada al-Sadr. U.S. soldiers were fired on late Monday during a routine patrol of the Shiite stronghold, which is home to more than 2 million people, said Capt. Brian O'Malley, spokesman for the U.S. 1st Cavalry Division. They returned fire as U.S. AC-130 planes targeted insurgent machine gun crews on the ground, he said. One person was killed and two were injured when their car came under fire during the fighting, said Dr.Mohamed Aboud of Sadr hospital said. Residents said they continued to hear loud explosions until dawn.