BAGHDAD - The U.S. military fired guided missiles into the heart of Baghdad's teeming Sadr City slum on Saturday, leveling a building 55 yards away from a hospital and wounding nearly two dozen people. Separately, the U.S. military said late Saturday that four Marines were killed on Thursday by a roadside bomb in Anbar province. The military also said that a U.S. soldier died of wounds suffered in a roadside bomb that struck the soldier's vehicle during a combat patrol in eastern Baghdad Friday. At least 4,071 members of the U.S. military have died since the beginning of the Iraq...