Help with my very angry toddler

im looking for some advise, I'm currently on holiday dealing with my very very angry toddler and I’m counting the days in my room until our flight home.

he has been referred 2 months ago suspected high functioning autism and adhd.

the past few weeks he has progressed from hitting children to scratching and pulling adults hair (parents, teachers or anyone near him)  in a violent rage. He has no empathy and my arms are so very badly scratched all over.

we are a family of 5 and my husband and I as well as our other kids are very calm people, we otherwise had a very happy home with no conflict at all but for the past year with what started with typical toddler behaviour has progressed into a real struggle. I don’t believe this is learned behaviour as he has never been subject or witnessed any anger or violence. 

He attends a very small nursery (12 children) he is youngest and no other children there have behaviour issues. Despite being the youngest at his nursery (30 months) he can count, name all colours, shapes, letters and now able to say a for apple, b for ball etc he can sort objects in order from largest to smallest etc but his behaviour is out of control.

I’m at my wits end with his challenging behaviour. 

can anyone relate to this and please give me some advice?