I have been told, repeatedly, that attacks like this are rare.
The Breed Of Peace.
Dog Attack Deaths and Maimings, U.S. & Canada,
Statistics compiling: U.S. and Canadian between September 1982 and December 2011, Merritt Clifton, (editor Animal People), shows the breed most responsible for serious injury and death.
Pit bulls:
77% of attacks that induce bodily harm
73% of attacks to children
81% of attack to adults
68% of attacks that result in fatalities
76% that result in maiming
http://washingtonexaminer.com/d.c.-officer-has-unexpected-pit-bull-encounter/article/2509755
Pit bull owners biting little girls? Happens all the time.