Three Americans – two soldiers and one civilian -- were killed on Saturday when a man wearing an Afghan army uniform opened fire on the group, according to NATO spokesman Lieutenant Quenton Roehricht. The incident is the most recent in a string of “green on blue attacks” in which Afghan soldiers and police turn their guns on coalition troops with whom they are meant to be working inside the county. The Associated Press reports the shooting arose from an argument and that the Afghan soldier had no known ties with the Taliban. Insider attacks, which peaked in 2012 leading to over 60 deaths, have been on decline this year. Afghan security forces are slated to take over after the scheduled U.S. withdrawal in 2014.