Is it normal to feel the need to kill a non-specific person?

Hi. I am a 17 years old boy, and sometimes I really feel the need to kill another person. Not a specific person, just anybody, really. Sometimes I sit in my room planning a kill. How I am going to kill the person, and how I am going to dispose of the body afterwards. Sometimes this urge/feeling inside of me become very strong, and sometimes I'm even about to do it. I think the only thing that has been stopping me, is that I don't think my plans are 100% solid. I have the feeling, that if I come up with a "perfect plan" I am really going to do it. Is this normal?