I agree with SunfallE. You deserve a big pat on the back, pal. What you did was not only helpful, but very responsible, too.
I can only imagine how difficult it is to get those images out of your head. Like the others, I also recommend that you just sit down and have a talk with someone. I don't think it's necessary to talk to a professional, just talk to anyone you think would be understanding or has experienced something similar.
One time I was crossing the street on campus, there's a lot of traffic and bikers, and pedestrians, and I heard a loud noise, and right in front of me a car hit a biker. I was standing in the middle of the street, stunned, and stupid, with my hands covering my face because I didn't know what to do. Then [B]ONE [/B]person out of the crowd of people had the sense to come aid the biker. So, yeah it's tough approaching that situation.
You know, you did a really good thing. Just give it some time and the images will fade. I think no one would mind you lamenting about something so traumatic. so talk to someone. =]