I had a similar thing happen here in my neighborhood with an attack. A VERY PREGNANT woman(8 months) and her husband(they live in the neighborhood) were walking their 2 dachshunds when my neighbor opened her door and a pit bull rushed out after them, it latched on to one of the dogs and tossed it around for a second then turned on the woman and grabbed her arm, the husband had grabbed a 4' or so 2x4 from the side of the adjacent house and needless to say he didn't stop until the dog was no longer breathing. Funny thing is I had actually confronted the owner of the dog a few days prior about it constantly barking and growling at my son when he was in my fenced back yard and they had it on a 4' lead on the back porch, the lady was pretty rude and just brushed me off. The FBI raided the house 3 days after the event arresting the girl and her boyfriend, they were involved in a bad gang that. I had no idea especially considering the type of neighborhood I live in, I had actually spoken with the man that lived thee and he seemed nice enough. There is really no crime here outside of a few break ins which is happening everywhere within 30 miles of the metropolitan area.
I am a firm believer in its not the dog, but the owner. I have a lot of experience in training dogs as I have trained quiet a few labs for retrieving and flushing, I am no professional by any means but have a pretty good understanding of it. Dogs have to be socialized, when they are held up in a house or yard with no socialization they become very hostile or very skidish, with a powerful breed like a pit bull they more than likely will become aggressive. My buddy has a huge pit bull that wants to lick you to death when you come around and lives indoors with a terrier, the terrier dominates it and it is hilarious, he will actually roll on his back and the terrier will stand on his chest. I also know someone who owns a timber wolf hybrid that is a teddy bear, he is the biggest dog I have ever seen but wont hurt a fly, but boy does he love rabbits...