An American soldier was seriously wounded at the Kandahar Air Field in southern Afghanistan from a gunshot wound to the head, but it was not from enemy fire, the U.S. military said Sunday.

The soldier, who was not identified, was flown to the U.S. military hospital in Landstuhl, Germany early Sunday, but was later moved to an undisclosed local hospital, due to the seriousness of his wounds, said Marie Shaw, a hospital spokeswoman.

The military declined to provide details about the shooting, which took place Saturday and is under investigation.

Earlier this month a U.S. soldier was killed in a firefight in eastern Afghanistan. Sgt. Steven Checo, 22, a paratrooper in the 82nd Airborne Division was shot while on a nighttime operation in the eastern province of Paktika, near the border of Pakistan. The assailants fled into Pakistan.

Checo was the 17th serviceman to die in combat in Afghanistan.