How to react ?

First of all I would like to advice you all, whenever you see a person with a disability just say
1- "Astaghfirullah ( 3 times)" ( for the one who is diable and May Allah keep us safe from any kind of disability )

2- "Alhumdulilah ( 3 times )" ( for Allah SWT made is perfect with no disablities )

3- "Subhaan Allah ( 3 times )" ( for His praise as he knows better what to do and what to not )

Secondly, Disability is from Allah, not from man himself, you do what you thought better that time, some kind of disabilities, like Mental disability specially in Young person Its dangerous we should keep ourselves away from them only if we dont know the person perfectly, as they can harm you anytime and they have more power than a normal man.

But in your case he was a child, you should give him a plate with naan in it, and let him sit and play with, he will never disturb you, and remember the kids always follow the person they like, regardless he / she is stranger or parents.

3rdly, we should behave normallu with physical disablities as they are normal and not mental case, they can think better, if they will get a chance, they will score better if they will get a chance, anyhow.. we should not let that person realize that he is disable try to handle him normal but help him not to feel his disability.

I hope you got my point.