A brief google news search yields many unfortunate stories about "Pit bull attacks." But many of them are misleading, and many of the dogs alleged to have "attacked" are mis-labled.
Take these two stories:
A lost American Bulldog wandered into a school in Fairbanks Alaska- where the staff reacted by locking the animal in a bathroom for "fear it was a pit bull." The family dog (identified later by microchip) was not threatening anyone, was retrieved easily and called "friendly" by animal control. Because the staff thought it was a pit bull- they locked it in a bathroom. (read more here.)
In 2003 one of the Queen's many welsh corgis was bitten by Princess Anne's bull terrier- the bites to its legs were severe and the dog had to be put to sleep. Not surprisingly- this article reports the corgi was "killed by a pitbull." Firstly, the bull terrier only injured the dog- and the dog had to be put to sleep later that evening by the vets- the bull terrier did not kill it. Secondly, the dog was a bull terrier!! a completely different breed than a pit bull. Thirdly, it was later disclosed that the bull terrier wasn't even responsible!! The media jumped to the conclusion, but it was one of Princess Anne's other terriers that bit the corgi.