Way back in the day we heard all the same stories about the breed du jour: GSD, Chows, Dobies, etc. It's the training more than anything.
i'm sure the dog "got jealous" and just started attacking. there's obviously more to the story than that.
anyone who's CLOSED MINDED and OBLIVIOUS enough to make a statement such as "pit bulls are killers by nature and can't be tamed" has about as much common sense as a rock.