obsession with killing

When I'm talking to someone, I suddenly think about killing them, and once the idea's in my head, I can't get it out. I plot how, when, where. I don't feel as if I'd be relieved to actually go through with it, but the concept of killing them consumes me for ages. For about an hour afterwards I get angry but keep it inside, and I can't stand to be around anybody for that time.

It's driving me crazy, I don't know how to stop it and I'm worried it might be some kind of psychosis. Please help.

(also mentioned in OCD forum)

I just think the best thing is to see a psychologist for help.Its so hard and even embarrassing when you ask, but its soooo worth it to look for help, especially when you think one day you could potentially hurt someone. I hope you get better! : )

Dear Friend, I implore you to get a psychological evaluation. Your condition can be helped.
What you think about - you will act out. This is very troubling and very dangerous. Get help now.
There are many reasons you may be struggling with this but, you need to find treatment for preventing these thoughts.
I also recommend you start praying to God for help.