Three bombers blew themselves up at a security checkpoint in al-Qadisiyya, north-west of Najaf, after an exchange of fire with security forces, local official Hussein Wahid told Anadolu Agency.
He said 25 people, mostly tribesmen, were injured in the attack.
No group has yet claimed responsibility for the bombing, but Iraqi officials often point the finger at the Daesh terrorist group, which overran vast swathes of territory in northern and western Iraq in 2014.