I saw a helper in my condo slap a 4 year old in her care who had pulled her hair. Not sure what to do. What would you do in my place?

If you know the parents of the child affected, best to let them know. Don't confront the helper directly because she can attempt to run or even hurt the child more. Be tactful and tell the parents what you saw.

I would definitely let the child's parent's know and bring it up to them first. It's really something that any parent would want to know about, so I'm sure they'll appreciate you approaching them!

Let the parent know or call the police. Meantime also try to have some evidence like video it, take pictures or have other witnesses incase the maid deny...

You should definitely try to find out who the parents are. I would want to know if this happened to my child.

thanks

Call the police.