Local security officials say a senior local leader of Asaib Ahl al-Haq, a powerful Shiite militia, was killed in the attack in Muqdadiyah, about 90 kilometres north of the capital.
Security there is largely maintained by state-sanctioned Shiite militias known as the Popular Mobilization Forces.
Hospital officials confirmed the toll. All officials spoke on condition of anonymity as they were not authorized to brief the press.
A bombing at a Baghdad market yesterday by the Islamic State group killed 73 people.