I believe not getting involved was the right thing to do. One of the first things I was trained in when I went through medic school was not to add yourself as another victim. You can not do anyone any good at all if you are down.
Personaly I would have gone a good safe distance away. Like at least a mile away, and then called 911. You do not know what was going on. It could have been a gang "jump in". You could have started to help the guys. Only to have them come at you too. Too many variables. I know the police would not have gone in with only one, or even 3 officers.
No matter how many times you do it and nothing happens it only takes something going wrong one time to kill you.