NATO says 11 people, including seven American troops, have been killed in a helicopter crash in southern Afghanistan.

The other casualties, according to a statement from the international military coalition, were “three members of the Afghan National Security Forces, and one Afghan civilian interpreter.”

It was not immediately clear what caused the helicopter to crash. ISAF said an investigation was underway. The Taliban issued a statement claiming that militants had shot the aircraft down, but the group often issues claims which later turn out to be false or exaggerated. . .