It's a natural defense mechanism that kicks in when someone suffers a traumatic injury. Sometimes gunshot and stabbing victims will say they don't feel any pain and will try to stand up and leave. Of course after a few minutes the nervous system gets back on track and the realization of what has happened causes lots of pain. My son was an EMT in Detroit and he used to tell me all kinds of strange stories about trauma injuries.He looked prett out of it after the helmet came off. Wasn't real coherent it seemed. Possible shock?