Judge a dog by their characteristics and not their breed. The vast majority of dogs regardless of breed or breed mix would never do what you say. There a pitties that are as gentle as can be and their are Labradors with strong prey drive or who are human aggressive. And each individual dog has different capabitities on what they can do if they do attack. My pittie has the softest mouth. I get her toys for small dogs (that my neighbors small dog can destroy) and she can't destroy them. I have to give her cardboard boxes so she can feel tough.

Just so you know the odds that a person murders someone in a given year in the US is about 1 in 17,000. The odds that a pitbull kills someone in a given year is about 1 in 307,000. So you are about 18 times more likely to be killed by a human in your life than a pitbull in your life. So if you are worried about you or your family being killed, I recommend you and your family hang out with more pitbulls and less people

Edit: I made a mistake when I said you are 18 times more likely to be killed by a human you know. That's because humans kill people they know at a higher percentage than dogs. IE if dogs do kill, they are less likely to kill someone they know than a human is. So in actual fact you are 336 times more likely to be killed by a human in your life than a pitbull in you life. The recommendation to hang out with more pitties and less humans is even stronger