Four ISIL militants wearing explosive belts detonated the bombs after a fierce clash at the headquarters of a paramilitary tribal fighters group early in the morning, according to the security source.
The headquarter is manned by tribal fighters and Iraqi soldiers, in the town of Garma near the city of Fallujah, some 50 km west of the Iraqi capital Baghdad.
The attack came after Prime Minister Haider al-Abadi on July 10 formally declared the liberation of Mosul from ISIL after nearly nine months of fierce fighting.