The majority of pit bull owners are not able to control their pit bull if it attacks.
Pit bulls are a public danger because very few pit bull owners, including those who have trained their dogs well, are able to stop an attack once it happens. The average pit bull attack lasts 15 minutes, and hundreds of documented attacks show that break sticks, chairs, steering wheel clubs and tasers are rarely sufficient to stop an attack once it starts.

• Repeated tasering will not stop a pit bull attack.
• Gun shots will not necessarily stop a pit bull attack.
• Bricks, a pole and a chair could not stop this pit bull from killing a child.
  http://www.dailymail.co.uk/news/article-3097618/Boy-5-mauled-death-pit-bull-despite-onlookers-beating-dog-brick-chair-try-stop-deadly-attack.html
• Onlookers armed with hoses, chains and bats tried to pull the dogs off but they weren’t able to stop this New York City attack.
  http://www.mirror.co.uk/news/world-news/artist-savaged-horror-pitbull-attack-6435495

Read victim stories and detailed reports of pit bull attacks at http://www.daxtonsfriends.com/category/dog-attacks-in-the-news/

Hospital study found that attacks by pit bulls are associated with higher morbidity rates, higher hospital charges, and a higher risk of death than are attacks by other breeds of dogs.
http://www.ncbi.nlm.nih.gov/pubmed/21475022

A Texas study published found a large proportion of dog-bite injuries treated at a major trauma centre were inflicted by pit bulls, and that those attacks were more likely to cause death, severe injuries, hospital admissions and higher hospital bills.
http://news.nationalpost.com/news/canada/controversial-pit-bull-bans-result-in-fewer-dog-bites-study

No other type of dogs attacks as viciously, often to the point of swallowing the victim’s flesh and body parts.
http://www.pennlive.com/nation-world/2015/03/owner_of_pit_bulls_that_partia.html
http://walkforvictimsofpitbulls.blogspot.ca/
http://www.mlive.com/news/detroit/index.ssf/2014/10/the_dogs_started_attacking_and.html
http://www.ctpost.com/news/article/Pit-bull-likely-ate-owner-s-hands-4980338.php
http://abc7.com/archive/9259360/
http://dogbitelaw.com/dangerous-vicious-dogs/canine-homicides-july-2006-to-present
http://www.wtsp.com/video/180452263001/0/Pit-bull-attack-victim-They-started-eating-me-alive

From the ASPCA Guidelines for Pit Bulls in its Shelters

• There are “cases of experienced handlers who had developed good relationships with the dogs over a period of months still being attacked without warning or obvious provocation.”
• Pit Bulls “ignore signs of submission from other dogs” and “give no warning prior to attack.” They add that this is “different than normal dog behavior.”
• “These dogs can be aggressive towards humans and more likely to cause fatal attacks to people than other fighting type dogs.”
• “Pit Bulls will climb fences, chew up stainless steel food and water bowls, destroy copper tubing of automatic water systems and conventional cages, and attack other animals through chain link fences.”
• “Pit Bulls can break through conventional cage doors and destroy typical epoxy paint on the floors and walls.”
• “Pit Bulls require special housing considerations” and “isolation from other animals if dog aggressive or have a high prey drive.”
• “Install a panic button in rooms housing Pit Bulls along with other restraint equipment in any room housing Pit Bulls.”