A string of deadly bombings in Baghdad killed 21 people and wounded at least 64 others Monday, as the U.S. military reported its first combat death in Iraq in about three weeks. The deadliest attack occurred in the Shiite slum of Sadr City when a parked car bomb exploded in a market, killing 10 people, including three women and four children, and wounding at least 28others, said Iraqi police and medical officials. A total of four bomb attacks struck the city over a two-hour period, primarily in Shiite neighborhoods where people were either shopping or looking for work. The first attack occurred at 7:30 a.m. when a car bomb exploded in the center of the capital, killing at least six people and wounding 16, said an Iraqi police official, who described them as mostly day laborers looking for work. Two other car bombs then exploded minutes apart in different markets elsewhere in the eastern parts of the capital, including Sadr City, killing a total of 12 people and wounding 40, said a security official.