Iraq is holding its first parliamentary elections since the US troops' withdrawal in late 2011.
Shiite, Sunni and Kurdish candidates are vying for 328 assembly seats in the deeply divided country, plagued by violence and corruption.
Prime Minister Nouri al-Maliki is eyeing a third term, even as he faces criticism by opponents who accuse him of failing to provide security and basic services to the nation.
The deadliest among today's attacks took place in the late dictator Saddam Hussein's hometown, Tikrit, 130 kilometres north of Baghdad.
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Elsewhere in Mosul, a gunman shot dead a soldier who was manning another checkpoint.
Medics confirmed the casualty figures. All officials spoke on condition of anonymity because they were not authorised to talk to the media.
Violence has escalated in Iraq over the past year, with 2013 seeing the country's highest death toll since the worst of the sectarian bloodletting began to subside in 2007. Iraqi security forces have been a favourite target for Sunni insurgents who want to undermine the Shiite-led government in Baghdad.