At least three of those killed were police recruits. The recruits were on their way from Ba'qubah in central Iraq to the Kurdish-administered northern region for training.
Also in Baghdad, gunmen opened fire on the convoy of Turkey's ambassador to Iraq, Unal Cevikoz. Turkey's Foreign Ministry said he was not injured.
Police say another attack in the capital saw gunmen killing five laborers.
Meanwhile, negotiations continue between leaders of Iraq's Shi'ite religious parties and Kurdish parties over forming a new government following the country's 15 December parliamentary elections.
Prime Minister Ibrahim al-Ja'fari, a leading member of the Shi'ite-dominated United Iraqi Alliance, met today in the Kurdish city of Al-Sulaymaniyah with Iraqi President Jalal Talabani, a key Kurdish leader.