I have a friend who was attacked TWICE by dogs. (Yes, he had seriously bad luck!) The first time was two Pit Bulls and a Rottweiler and the second time was a single Pit Bull. In both instances I think the dogs went after my friend's Golden Retriever and then turned on him. Both times involved irresponsible owners who let their dogs get out of the yard and dog-aggressive dogs. He got pretty jacked up both times. Incidentally he now owns a Rottweiler who is gentle as a lamb, as do I. We have no bias against Rottweilers.
I come across Pit Bulls fairly regularly and I'm always ready to pepper spray them or a more lethal alternative but I must add that the circumstances of my coming across them are not friendly and the people who own them are even less friendly. I blame that on the 'hood mentality to have a guard dog that lives outside 24/7 and has zero socializtion or training.