From your link:
32 U.S. dog bite-related fatalities occurred in 2013. Despite being regulated in Military Housing areas and over 700 U.S. cities, pit bulls contributed to 78% (25) of these deaths. Pit bulls make up about 6% of the total U.S. dog population.
A similar story happened here in the Houston area. Same breed of dog, same MO. Pitbulls got over the fence and into the house via the doggy door and killed 2 Jack Russells. This is a good reason to not use doggy doors.