Yes! We must defend ourselves.
I found out from my friend that lost his neighbor, in TN if you are at a public dog park, and one of the pits attacks your dog, you’re not allowed to use your carry-permit gun to shoot the pit bull. You are only allowed to shoot if your own life is in jeopardy (not sure about another person, but that’s probably okay to shoot in that circumstance). So basically you have to get between the pit and whatever dog it’s mauling in order to have legal pretext to shoot.
Pit bulls and “mixes” need to be banned from dog parks (and they are probably, if you interpret “vicious dogs” as posted on most dog park signs at their entrances — but most pit owners don’t think their dogs are “vicious”).
It’s too risky for the public and the other dogs to allow this breed to mingle with the rest of us.
“You are only allowed to shoot if your own life is in jeopardy”
In which case, anyone would be stupid not to have at the ready a darn good story, and hope other owners nearby would support you. The pit owner might object, but it would be his word against yours.