The Taliban have claimed responsibility for an attack at the Kabul airport in which a gunman shot and killed three American contractors and one Afghan man.

Friday's claim came in a message from the Taliban spokesman, Zabihullah Mujahid.

A U.S. and an Afghan official said the shooting happened in the early evening hours Thursday, at the North Kabul International Airport complex. That section is military.

In a statement, Mujahid identified the attacker as Hessanullha from Laghman province. He said the Taliban fighter had infiltrated the ranks of Afghan forces to stage the attack and wore an Afghan police uniform.

The Afghan official, who is with the Defense Ministry said the attacker was in an Afghan army uniform. Both officials spoke on condition of anonymity because the investigation is still ongoing.