Yes, absolutely. You don't have to be middle eastern or belong to a specific organization to be a terrorist. A terrorist is somebody that instills fear and terror, and this guy certainly is one.
If your talking about the Sandy Shooting, then no. He's was just a sick, mental person. He worked for no organization of any sort.
He's actually the bro of the killer, merry xmas, bloody xmas.:[p He reportedly reported it.