A mortar shell exploded on a street in northern Baghdad, killing three women in their homes. Elsewhere, soldiers discovered the bullet-riddled bodies of six men wearing handcuffs - apparently the latest victims of sectarian death squads. Three car bombs also went off nearly simultaneously Friday in a market area of southern Baghdad, killing one person and injuring seven, police said. The mortar shell detonated about dawn, killing a mother and daughter in one house and a woman in an adjacent house, police reported. The houses were located near a Christian church and half a mile from the Interior Ministry, but the target was uncertain, police said. The car bombs went off one by one in a shopping district in Dora, a predominantly Sunni area and one of the most dangerous in the capital. The cars were parked in separate parts of the Assyrian Market, a sprawling collection of stores and street vendors selling clothing and foods. While March was a bloody month for Iraqi civilians, the death toll for American military personnel stood at least 29 - the lowest monthly total since February 2004, according to a count by the Web site icasualties.org.