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 U.S. 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.
The area is at the doorstep of Iraq's western Anbar province, which is dominated by Sunni Arabs and is the birthplace of the Sons of Iraq movement, also known as Sahwa, or the Awakening Councils. Members of the group once fought U.S. forces, but later switched sides to fight Al Qaeda in Iraq.
Remnants of Al Qaeda and its allies are blamed for many of the bombings and other attacks that continue to plague the country.
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.