Hmmm, well I have mixed opinions on the subject.
I'll be blunt, dogs are social animals and it's very rare when a domesticated dog is going to attack someone. While certain breeds are "insane" being bred for violent tendencies, in most cases being raised as a pet as opposed to a combat animal is going to mitigate those.
Dogs, especially formidible ones also tend to be very protective of those in their territory (who belong there) and/or packs. There are many stories of dogs coming to the aid of children and so on.
Dogs also have a tendency to roughhouse when playing, and in most cases when they realize they aren't the alpha will take abuse more from a perspective of "what did I do wrong" rather than "enemy! Attack".
Oh sure, I know there are execeptions, but from the way this sounds I'm guessing that either there is something very wrong with the noises that game makes (it should be tested around dogs) or more likely that the girl was trying to do something beyond the pale with the dog. By this I mean more than just kicking it.
It's also possible that if she was rough with the dog, the dog decided to play with her, and given the relative size there was an accident. Consider that dogs like to nip when they play, a fully grown bull mastiff nipping a 9 year old can easily go horribly wrong. Some dogs aren't used to playing with children if they aren't around.
To put things into perspective my dog is a Pug, he weighs about 25 pounds. When walking him, some of the neightborhood children like to pet him and such. However he tends to be very excitable so I need to watch him. When dealing with a little kid coming to pet the doggie a 25 pound dog is still pretty big compared to the child and while he does not nip/bite (I've trained him out of that) he does like to rear up and lick people and stuff. leaning up against a kid's chest with his claws and so on he could do some damage especially if he's excited so I have to keep a careful eye on him, and a firm hand on the leash. I've avoided accidents as a result.
The point here being that it could have been something like what I watch out for, but with a dog who wasn't trained out of nipping people.
Just some rambling thoughts.