WASHINGTON — Eight Islamic State fighters were killed when they attacked an air base where U.S. and coalition forces are training Iraqi forces.

Army Col. Steve Warren, a Pentagon spokesman, said that initial reports Friday showed that all of the IS attackers were killed by Iraqi troops at or inside a gate to al-Asad air base in the western province of Anbar.

There are about 400 U.S. troops at the base, but Warren said none of the American forces were involved in the fighting. He said the U.S. troops were about two miles away, in a different section of the sprawling air base.

U.S. unmanned surveillance aircraft and Army Apache attack helicopters were sent to the scene from Baghdad, but the attack was over before they arrived, so they did not engage in fighting.

There are currently nearly 2,600 U.S. forces in Iraq. Of those, about 450 are training Iraqi troops at three bases across the country, including al-Asad. Forces from other coalition countries conduct the training at the fourth site, in the northern city of Irbil.