Violent behaviour

Agressive behaviour is usually caused by confusion or the need of acknowledgement. It is not at all easy to be an autistic child and to have a world of people around you that don't understand you! 

Have some quality time with your child, so that he feels you close to him. You want him to feel that you enjoy him, without any demands. 

Nothing els for the moment. Just BE with him or her. Your life will change, I guarantee it.