Someone on a killing rampage isn't necessarily engaging in terrorism. Terrorism is about intent. If the intent and reason behind the killings is to instill fear into a community or coerce them into providing him with something, then he is a terrorist.
If he's killing just for the sake of killing or because he's bent in the head, then he's not a terrorist, even if fear is a byproduct of his actions.
If he's killing just for the sake of killing or because he's bent in the head, then he's not a terrorist, even if fear is a byproduct of his actions.