I think an apology is good, and making sure the kid is ok. I saw one that I thought was handled well.
Basically, at a local science fiction convention, there was a guy in a very cool, but bulky, costume. He was going down the escalator, and this little girl (maybe 5 or so?) got too close behind him, even after her parents warned her not to. He lost some balance and started to fall backwards, and the woman behind him and the little girl managed to hold his weight off the girl with her legs, and someone else stopped the escalator.
So the girl wasn't hurt, except maybe a small scratch or two, but she was upset and crying. And her parents were comforting her, but also telling her "we told you not to stand so close to him." They didn't blame the guy in the costume at all (he did apologize, though).