Very sad. I feel for the parents.
I too wonder what the 12 year old boy had done.

We were discussing this yesturday with my family.
My Aunt said no Dog should ever turn on it's own family.
I agree up to a point. But....some Dogs do
not have what we would consider a perfect temperments.
(we tend to forget they are animals.)

Just look what some of us humans do to others.

Unfortuantely we will not know what happened.
I bet their were prior warning signs from
the pet or pets involved and also how their son
treated his dogs.