The one I dealt with was quite different. He weighed 90-100 pounds. Built like a fire plug with no neck.I had a similar situation. My dog was leashed, I was in my yard, and my dog got into it was a roaming pit bull. My dog definitely bit first.
I reached in to break it up and it didn't go so well for me. It did get broken up though.
I leashed the pitbull, walked around the neighborhood (bleeding) until someone recognized it and I dropped it off. Apparently the kids let the dog out.
I didn't report it for two reasons:
1) My dog started it. (even though he was leashed on my property)
2) I know what would happen to the pitbull, that seemed to be an otherwise well mannered dog in terms of people interaction.
He attacked silently from behind. When I blocked him he whirled and rushed me without a sound.
His intent was to kill, not merely fight. (including me) My Yorkie weighs 6.5 pounds.
A neighbor said someone about a mile away has three PBs raised for fighting.
We have several "rowdy" dogs in the neighborhood. It's easy to settle them down.
This one was dangerous.