Definitely sounds like ocd intrusive thoughts. That's the thing, they are just thoughts. Some therapy could be beneficial to you. Learning how to cope with these thoughts is important. The more you try to push them aside the stronger they get. Next time you have the scary thought pop in your mind think lightly...it's just a thought. Then let it go and direct your thought elsewhere. It takes time to do any right. It helps to find a therapist to direct you in this. You are not a serial killer. It's completely normal to have these thoughts. Those that have ocd tend to get stuck on the worst thing our brains can come up with. It will be ok. You can fight this and not live in your own personal he'll!