ISIS claims, "Abu Abdullah al Amriki," an American suicide bomber was the main preparatory in the attacks on security officials in Iraq’s Baiji on Wednesday.
Baiji’s area north of Baghdad has one of the biggest oil refineries in the world. Iraqi forces, backed by US air strikes and Shiite militias are battling the ISIS insurgency in the region.
"Abu Abdullah al-Amriki" detonated an explosives-rigged four-by-four near the town along with three other attackers -- two Tajiks and an Iraqi -- blew up other explosives-rigged vehicles in the Baiji area, the militant group said, without specifying when the attacks took place.
Thousands of foreign recruits join ISIS, from Europe and the United States.
Another American carried out a suicide bombing against Iraqi forces in the city of Tikrit earlier this year, according to ISIS.
Much of western Iraq is under ISIS control, the Iraqi army and Shiite militias gained significant ground north of the capital, however constant ISIS suicide bombings and car bombings occur across Iraq, killing hundreds.
Recently a car bomb ripped through a wholesale food market in Sadr city in Baghdad, killing around 100 civilians.