"Just tell Your Wife to Mind her own Business"

So yesterday evening I had a crazy experience. I was playing on our front lawn with Kellin when I heard shouting coming from the house across the street. I walked over to the side of the house to get a look at what was going on and saw a man and a woman yelling at a younger man. The older man had apparently been doing some yard work and was holding a rake. As the two men were yelling at each other the older man ran at the younger man and literally bashed him in the face with the end of the rake!!! I did the first thing that came to my mind which was to start screaming at the top of my lungs "STOP!! STOP THAT RIGHT NOW OR I'M CALLING THE COPS!!!" I then ordered Kellin into the house to get Kade and get a phone and continued to scream that they'd better stop or I was calling 911. The woman yelled back at me to mind my own business as the younger man walked around to get in his car. There was something on the top of his car that he grabbed and threw at the older man. I screamed again at the younger man "GET IN YOUR CAR AND DRIVE AWAY RIGHT NOW OR I'M CALLING THE COPS!!" And luckily he got in his car and after a few explicit profanities drove off. The woman kept yelling at me to mind my own business and I yelled back at her "IF IT HAPPENS IN MY NEIGHBORHOOD AROUND MY KIDS, IT'S MY BUSINESS!!!" Finally, Kade came out and asked if everything was okay, to which the woman again yelled, "Tell your wife to mind her own business" to which I of course yelled back "IT IS MY BUSINESS WHEN IT HAPPENS IN MY NEIGHBORHOOD AROUND MY KIDS!" My hands were shaking for the next 15 minutes as I walked back into the house and locked all the doors. My heart was pounding as I tried to calm down not only because I was scared but also because I was ticked! How dare that woman tell me it's not my business! I have been thinking about it since and wanted to throw this question out - when is it our business and when should we stay out of it? Should I have just grabbed Kellin and came into the house? Or did I do the right thing by getting involved? I have to believe that I did the right thing by getting involved because who knows what else would have happened? But then I was worried all night that they might come over and do something to our house or yell at me the next time I see them out. But who cares right? If we tolerate that kind of stuff in our neighborhoods or just look away when we see something bad happening we are contributing to the problem. My reaction was immediate and almost instinctual, and I guess that is probably just the way I was raised, to speak up when I see something wrong. I'm curious though, what would you have done??