Pentagon officials promised an investigation into an incident today in which a US soldier in a watchtower opened fire on an Afghan boy, shooting and killing him outside the Bagram airfield in Parwan Province.

Details are still scant on the incident, but the soldier claimed the boy had “what looked like an automatic rifle” when he fired. Officials never did say what the object turned out to be, though it was evidently not a gun.

The killing added to tensions around the airfield, which has seen numerous incidents riling locals, and villages from the surrounding area organized near the base to protest the killing, though they have since been dispersed.

Though the US presence at Bagram isn’t as large as it once was, the site has been a source of controversy for years, and in 2012 sparked a massive protest when US military personnel were caught burning Qurans at the base.