JNU case: Who are actually behind the masks?

Masked goons attacked Jawaharlal Nehru University's students in which more than 18 were injured. Among them were few professors as well. But the question here is, who all are actually behind the attack? Howcome the masked goons knew all about the university? Howcome they attacked few selected students and why did the goons include a girl among them? Is it a fight against hiked-fee or politics? Take a look at the report to know more.