Security officials say gunmen have opened fire on a checkpoint in central Iraq, killing five anti-Qaida militiamen.

Authorities say the attackers struck the Sahwa checkpoint early Saturday in Khan Bani Saad, about 35 kilometers north of Baghdad in Diyala province.

Members of the Sahwa are Sunni tribesman who have taken up arms against al-Qaida, helping to prevent Iraq's sectarian strife from becoming a full-scale civil war.