It is not abnormal to feel impacted by the things that you see in your line of work. In fact, it is absolutely normal to be impacted in some way by many of the things you encounter. Here is one first responder's experience with his work, experiences, and his realization that he was suffering with PTSD.
http://www.npr.org/2010/12/30/132476507/first-responders-rescuers-face-p...