When an enemy is not readily identifiable, and they are not fighting a conventional war. Things like this are bound to happen. The Germans were very identifiable as German soldiers, especially those of elite units such as the Waffen SS.
But this is not a conventional war and this is not a conventional enemy. We have Islamic who prefer to hide among the general population, only confronting soldiers and civilians via cover methods such as using remote detonated bombs and suicide bombers dressed as ordinary civilians. As long as our enemy continues to utilize such methods, right or wrong, we will continue to suspect those of Muslim background.