So this may not be as much gifted related, as to parenting related. But I assume most of us have a kid that is enthusiastic about learning, and that being possibly hampered is a big concern for us.

I have a 4 year old who is always excited about school, enjoys learning, playing, and is a very good listener in class.
Morning class is perfect, does his work, teacher is great! At 11:45 they switch to the afternoon class.

Afternoon class I believe there is a kid that is proving to be difficult. He has some behavior issues of not listening and hitting other kids. My kid has never been hit.

The problem is for the first time on the way to school today, he wanted to get picked up after morning, but before afternoon class. He said, after a lot of prodding, that some kids are not nice in class, I asked why they are not nice and he stated that they hit. After clarifying that he wasnt hit, I could tell that this situation is making him sad, on the verge of tears (not crying, just sad enough to have tears run down his face).

Talked to the afternoon teacher, she confirmed that there is a kid hitting, etc. They are working on their end to try to get the situation to a resolution. She was also disheartened to hear how this was affecting my kid, because he does a pretty good job and is generally enthusiastic.

I told her I understand, I just want to know what is going on in the class, and try to set my kid up for success. That includes how to deal with an environment like this. So I'm trying to figure out what are some coping mechanisms for my son to deal with the situation.
I have google'd but my google-fu must be weak on this subject. I have found lots of links on how to deal with the disruptive student, but now how to have a kid in the classroom deal with the emotions from the situation.

TLDR: Kid in Afternoon Class hits other kids (not mine), it makes my kid sad, and not as excited about the class as he normally is. What coping strategies can I provide my kid in this situation, to keep him excited about his class?