the northern Shiite-dominated district of Qahira, four people were killed and eight others injured when a roadside bomb exploded near a market place, police said.
Also Tuesday, one person died when a roadside bomb targeted the convoy in central Baghdad of a Shiite government official and former member of the Iraqi Governing Council.
Ahmed Shiyaa al-Barak, who currently serves as the head of a government real estate commission, escaped the attack without injury. Five of his guards and four bystanders were injured in the bombing, police said.
Gunmen also shot dead a policeman in eastern Baghdad.
U.S. officials say attacks in the Iraqi capital are averaging about four a day -- down nearly 90 percent from levels of late 2006, when Shiite-Sunni fighting was at its high point and just before the U.S. troop surge that helped bring down violence in the capital.
But Tuesday's blasts -- coming a day after a string of bombings killed 10 people -- mark an increase in bloodshed in Baghdad and underscore that extremists remain a threat.
In the northern city of Mosul, a suicide bomber rammed his car into a passing police patrol, injuring four officers, police said.
Two other attacks took place Tuesday in Mosul, which has also experienced a spike in violence in recent months. A roadside bomb struck an army patrol, injuring an officer, and a gunman opened fire on a policeman, wounding him.
Elsewhere, the U.S. military said one civilian died on the scene of a road accident with coalition troops near the city of Tikrit, 80 miles (130 kilometers) north of the capital.
A second Iraqi died after being rushed to an aid station.
Iraqi police said an American Humvee ran over four Iraqis while they were trying to hang a banner in the middle of a road, killing two and wounding two others.
The Iraqi officials spoke on condition of anonymity because they was not authorized to release information to the media.
Violence has dropped in Iraq since the U.S. military and Iraqi security forces have gained the upper hand against insurgents, but scattered attacks still occur almost daily.
