Unknown person dressed in an Afghan uniform killed two American advisors - military and civil servants -  near the NATO base Kabul, reports the BBC. Another three Americans got injured -  one military and two civil servants. Militaries opened fire in response and killed the attacker. According to the Afghan Ministry of Defense, the attack in Kabul took place at 11 a.m. There are about 13 thousand people under the supervision of the NATO-led international military contingent in Afghanistan.