Question about the mind?

About seven weeks ago I started to notice a particular problem. This problem is I continue to have violent thoughts about hurting people(and by hurting I mean killing) especially the people that I love, such as my mother and father. I do know killing is wrong and it's something I would never ever want to do to any human being. I can manage to block it out of my mind willfully, but sometimes I get a little more scared of my thoughts and it causes me more anxiety because I feel like I would act on impulse. the weird thing is that this started to happen to me after I saw the movies Halloween, and Prom night and watched a doentary on serial killers on Tru tv. Before seven weeks ago I was thinking with my normal though process, such as hanging out with friends, thinking about what I'm going to eat or what I'm going to watch on Tv, you know normal things that people think about. I'm 16. Should I be worried? Is there something wrong with me?