Brother getting bullied

My brother called me this afternoon in tears. He is autistic and he said some kids from school (he's in mainstream) didn't want to be his friend. He gave me his Facebook login to see the messages. These teenagers have a group chat with my brother included openly talking about how much they don't like him. Saying that he ugly and disgusting he is and making fun of him saying that girls have crushes on him (when they don't) and he should text them and they tell him what he should say because he doesn't know any better. They also made an event called (*my brothers name* is so sexy don't you want to bang him). I'm crying reading this. He went to elementary school with these kids and no longer goes to school with them and I really don't know how to handle it. My mom died so my dad and I are his main care givers. They have also been leaving mean spirited comments on everything enposts on Facebook and tagging heir friends on purpose to embarrass him. How would you guys handle this? 
UPDATE* he says he is worried for me to report it because a couple of the kids involved go to his high school and he's terrified he'll be subjected to even more crap if he's a "snitch". We live in Ireland and the laws are definitely not zero tolerance here which is so sad but I plan to forward everything up the parents, school and police for safety. I wish I could be with him every second so he doesn't have to deal with stuff like this. He's the nicest person I've ever known and doesn't deserve such horrible treatment. Sad part is he thinks these people are his friends because they include him in group chats. He isn't aware that 90% of the time on Facebook they are making awful and inappropriate jokes at his expense. It's so sad that intolerant kids still exist in the world. Where the hell are their parents?