Helping my child understand a child with behavioral issues in his classroom...

Hi /r/parenting!My son is in second grade with another student that has been diagnosed with ADHD and ODD. His parents send us a nice little letter every year trying to explain the struggles he has in class and that they appreciate everyone's patience with him.Today, the child jumped on a girl in the classroom and hit her across the face, causing her to cry. The child was removed from the class, but then brought back in. He then kicked a trash can into the wall, and was sent home.My son was very distressed about the whole ordeal, and is afraid that this child may lash out on him in some way.I am at a loss with how to explain this to my son in a way that can comfort him and make him more understanding. I know that this child's parents just want the best for their son (we are the top performing school in the district), and I know they are doing everything they can to help. I just don't know where the line is drawn, and I don't know how I would react if my child was the one attacked today.I'm just looking for some advice, maybe even from other parents in the same situation, or parents with children with similar disorders. I'd love to be able to help my son know how to be a good friend to his classmate.Thanks guys. via /r/Parenting http://ift.tt/2bGx3rA