A suicide bomber rammed his car into a U.S. military convoy as it was passing through a crowded market in eastern Afghanistan on Thursday, killing at least 20 civilians and an American soldier, officials said. The attack outside Jalalabad, the capital of the eastern Nangarhar province, also wounded 74 civilians, said Ajmal Pardes, a provincial health official. Separately, an explosion in southern Afghanistan on Wednesday killed two NATO soldiers, the military alliance said in a statement, without disclosing the soldiers nationalities.The bomber struck the convoy near a crowded market in the Bati Kot district, where people were trading sheep, cows, goats and other animals, said Ghafoor Khan, the spokesman for the provincial police chief. Lt. Cmdr. Walter Matthews, a U.S. military spokesman, said at least 20 civilians and a U.S. soldier were killed. The soldier's death brings the number of U.S. troops killed in Afghanistan to at least 148, the highest number of troop deaths per year since the U.S.-led invasion in 2001. There were 111 U.S. military deaths in Afghanistan in the whole of 2007. An Associated Press photographer said that an American military vehicle, two civilian vehicles and two rickshaws were destroyed in Thursday's blast.