The late morning attack in the capital's western Mansour neighborhood came a day after a car bombing killed five people outside a Baghdad police station during an early morning shift change.
Monday's blast also wounded at least nine people and damaged several shops, according to security and hospital officials.
Although violence has fallen sharply in recent years, Iraqi security forces still struggle to stop deadly attacks from happening as US troops prepare to withdraw.
The attacks threaten to further destabilize the country as political leaders jostle for control three months after indecisive parliamentary elections.
A third person was killed and eight were wounded when a bomb stuck to a minibus exploded in Baghdad's overwhelmingly Shiite slum of Sadr City in the morning, police and hospital officials said.
Attackers shot and killed a father and two of his sons at home in the Al-Zaidan village, near the town of Abu Ghraib, west of the Iraqi capital.
A police official said the dead man's brother is a prominent member of anti-insurgent Sunni fighters known as Sons of Iraq, and that the gunmen likely believed he was staying in the house.
In another nearby village, Al-Abid, gunmen forced the families of four policemen out of their houses at dawn and then bombed the buildings, police said. Officials said many in the area are Sahwa supporters, though others remain sympathetic to insurgents.
All officials spoke on condition of anonymity because the were not authorized to speak to the media.
Meanwhile, the US military in Iraq says it has detained a soldier who has been identified as the source of a leaked video showing Army helicopters killing two journalists in a 2007 shooting.
The military said Monday it is holding Army Specialist Bradley Manning of the 2nd Brigade 10th Mountain Division in pretrial confinement in Kuwait and that he is suspected of releasing classified information.
The 22-year-old was identified by website Wired.com as the source of a video leaked online in April. It shows Army helicopters killing two employees of Reuters news agency.
The military did not refer to the video Monday. It said only that it "takes the management of classified information very seriously" because it affects national security.
