Pit bulls are no more dangerous than other dog breeds. Neither the CDC or the AVMA support breed specific legislation.
In fact, if you look at temperament tests, they do as well as pitbulls and better than some common breeds not deemed to be dangerous
http://www.animalfarmfoundation.org/item.php?item=73The person who let this dog out needs to be held accountable, and pit bulls are unfortunately a dog that a lot of bad people get, but if you ban the breed, they will just choose another breed to do the same with. And people who are responsible pit bull owners will have to put their pets to sleep. Nothing would be accomplished.