keista made a very good suggestion. Ask a lot of why questions to find out what REALLY caused all this. It could have been something earlier in the day that he had to process and then reacted later, at home. That is very Aspie behavior. With communication issues, he may have said it was caused by one thing but it was really caused by some other thing some other place and he didn't realize it.
This sounds very Aspie to me. We have had two similar instances like this at school and it turned out it was something that was said at home before he ever left that was the "root" of it. Of course, the school didn't ask the whys, I did.
