I wonder what made the bird attach like that? Do you think the kid got to close and it might have felt threatened? Good on the dad for running after it.
As a kid we had the same issue with a turkey. I have no idea what his problem was, but he would attack people every chance he got. For months we had to keep a stick by our front door because the second you went outside he would chase you and attack.
We eventually corrected the problem with turkey dinner!