In other news, police said the bodies of eight men were found in two districts of the Iraqi capital.
Violence was also reported in the northern city of Kirkuk and in Mahmoudiya, south of Baghdad.
The latest attacks come after Iraq's new prime minister-designate pledged on April 22 build a national unity government bringing together Shi'ites, Sunni Arabs and Kurds.
Shi'ite leader Jawad al-Maliki has 30 days to assemble the cabinet.
Following his nomination, al-Maliki called for all Iraqi militias to be integrated into government security forces, saying weapons belong only in the hands of the government.