Have you ever shot an airsoft gun? Like someone else said upthread, getting hit with a rubber band hurts worse.
Witness say that he then he gave it to his daughter who rode around the park on her bike and pointed it at two year old kids.
If you were a parent, wouldn't you be mad?
Here is a picture of the father shooting it over top of the baby carriage. Next to him is his son who he let shoot it. Sorry, I can't defend this guy. He is incredibly stupid.