At least 21 people were killed as suicide bombers attacked members of Iraq's security forces as they began voting to elect members to the 328-seat parliament in the country's first election since the withdrawal of U.S. troops in late 2011.
Attackers wearing police uniforms struck polling centers around Baghdad and north of the city, while roadside bombs targeted military and police convoys, leaving more than 40 injured.
No group has claimed responsibility for the attacks, but Sunni militant groups have previously targeted security forces and members of the nation's Shi'ite majority.
Early voting began Monday for those unable to cast their votes in Wednesday's parliamentary elections, including security forces, hospital and prison staff, as well as, patients and inmates.
Analysts say voters will likely cast ballots along sectarian and ethnic lines with no single party expected to win a majority.
The elections, a key test for the country's fledgling democracy, take place against a backdrop of rising violence and fighting in western Anbar province to expel al-Qaida-linked groups.
Some information for this report contributed by Reuters.