The deaths fueled immediate speculation that it was another "insider attack" of the type that has been so common throughout the NATO occupation of Afghanistan.

Afghan officials, however, say they are still unclear exactly what the reason was for the shooting, and that they intend to conduct an investigation into the matter.

Details on exactly what started the incident are scant, though in the past such shootings have not always been the case of "Taliban infiltration," and at times such shootings were simply the result of arguments.