The Pentagon says a U.S. soldier was wounded slightly when fired upon by an unknown person outside a base in central Iraq where U.S. troops are training Iraqi soldiers.

A Pentagon spokesman, Col. Steve Warren, said this marked the first time an American military member has been wounded by ground fire since the U.S. began training Iraqis as part of the coalition effort to defeat the Islamic State group.

Warren said the incident happened on Wednesday.

The spokesman said the soldier at the Besmaya training site received a "non-life threatening laceration" on his face. He was treated and returned to duty. Warren said the wound may have been caused by a ricochet off a concrete wall on the base's perimeter.

Warren said U.S. soldiers returned fire.