I remember earlier this year, I was coming out from Costco, and in the carpark two asian guys were fighting. I sent my wife and daugther in the car, told them to stay in and threw myself into the fight, shouted and break up the fight. Each went to their own in few minutes, I went to my car and my daughter was calling me a hero.
Obviously, it felt very plesant, but after the euphoria went away, I stopped for a minute and thought about it. What if one of them had a knife or a gun and I was wounded or even killed? Why was I so stupid to think about somebody else and not about my family, i could have been killed.
There are many stupid and crazy people walking free in our society, you never know what plans or weapons they carry with them.
As others have said, leave the bravado or the willing to help by fighting, just make sure you're safe and your close people are too, walk away and call the Police.
My two penny...