That the family had for over 8 years without a single prior violent incident. The attack went on for ten minutes leaving the baby boy and 2 year old girl dead and the mother with an "uncountable amount of stitches and injuries"
Stuff like this makes me so sad but scares me too, I've always been scared of big dogs, but it's something I try and keep at bay and not put on to my kids. My brother and his wife have 2 Rottweilers who I was petrified of at first but have learnt to be around, they are very calm but stuff like this makes me feel like I can never take the kids round there again because what if they just turn?
I know about the whole it's owners not breed spiel, but stuff like this brings that into question surely? You can never truly know what a dog might do can you? 
Link if anyone doesn't know what I'm talking about. RIP to those beautiful kids.
www.independent.co.uk/news/world/americas/baby-sister-killed-pitbulls-memphis-b2197336.html?amp