According to police, the CCTV footage shows that five people, including the deceased, were seen fighting inside the bathroom.
"After scanning CCTV footage, we transferred the case registered under Section 304 to 302 (murder). We have found that he had a fight with four students. He fell down after he received punches during the fight and died later," Deputy Commissioner of Police (northeast) Ajit K Singla told ANI.
"We have apprehended three students till now", he added.
The boy was found unconscious inside the school premises on Thursday. When taken to hospital, doctors declared him dead, after which people staged a protest outside the school.
The Uncle of the deceased had told ANI, "When we came here, they refused to admit him. We then took him to another hospital which declared him dead. He had died over two hours ago. Looking at his body we realised that he had been in a fight with someone." (ANI)