Iraqi officials say gunmen have shot dead seven members of a government-backed militia near the northern town of Tuz Khurmato.
Iraqi police reported the attack Friday, adding an eighth militia member was very seriously wounded. A police officer said gunmen dressed in military uniforms gathered the militiamen in a group at a checkpoint, took them to another area and shot them.
No one has claimed responsibility for the attack, but al-Qaida-linked Sunni militants in the past have carried out attacks on the militia members, who are pro-government Sunnis known as Sahwa and viewed by the militants as traitors.
The Sahwa rebelled against al-Qaida and joined forces with U.S. troops at the height of the Iraq war several years ago.
Earlier this week, al-Qaida's Iraqi wing claimed responsibility for a series of car bomb blasts in Baghdad that killed at least 28 people and wounded around 100 others in predominantly Shi'ite districts.
The al-Qaida affiliate, Islamic State of Iraq, said Monday it carried out the attacks in Baghdad to take revenge for perceived state repression of Sunni Muslims.
The wave of violence coincides with a political crisis that has seen the Iraqi government plagued by infighting among sectarian factions and pressured by almost two months of protests in mostly Sunni regions. Many Sunnis accuse Shi'ite Prime Minister Nouri al-Maliki of marginalizing and discriminating against their community.