As upset as you might be from witnessing child abuse, do not confront the abuser. Alert others in the area whose job it is to handle the situation — such as management or security.
If the abuse is taking place at a location where there is no management or security, contact your local authorities.
Offer to help if the adult can't control the situation at the moment. For example, if the parent is lashing out because his/her child has thrown store merchandise onto the floor, ask if you can help to pick it up.
Contact them with the physical descriptions and license number that you have written down. Alert them to the situation and let them know that somebody needs to look into it.
