Belmont Resident, my heart is heavy with sadness over the loss of your little girl in such a tragic manner. This dog is a ticking time bomb and the parents of these children are insane to keep them.
A pertinent question from this informative website about the history and nature of Pitbulls:
http://www.dogsbite.org/dangerous-dogs-pit-bull-faq.php
Q: Why does my friend say, "Pit bulls are dog-aggressive not human-aggressive?"
Due to selective breeding for the purposes of dogfighting, pit bulls are highly dog-aggressive. This aggression is not limited to dogs; pit bulls frequently kill other companion pets and domesticated animals. Leading pit bull education websites warn pit bull owners to, "Never trust your pit bull not to fight." These same websites also state that pit bulls should never be left alone with another dog or animal.16 The practical question is: Why is "pit bull dog aggression" tolerated at all?
Pit bull dog aggression is unacceptable for two reasons. In many instances it leads to human aggression. A common scenario is the following: A loose pit bull attacks a leashed dog being walked by its owner. The owner gets seriously injured trying to stop the attack. In 2009, two human beings suffered death due to pit bull dog aggression: Rosie Humphreys, who had been walking her two poodles, and Carter Delaney, who had tried to protect a smaller dog in his home.
Secondly, far too many beloved companion pets and domesticated animals suffer a violent death by the powerful jaws of pit bull terriers each year. In some instances, these attacks involve pit bulls charging through screen doors of private homes -- in a home invasion attack -- to kill the pet living inside.17 Owners of the pet are then forced to watch as their pet is disemboweled by the pit bull and pray that the dog does not turn its attention on an innocent family member next.