While monitoring and controlling inmate movement into the bathroom, due to inmates grouping up and smoking in the bathroom after lights out, the Officer was approached by an inmate that was verbally harassing the Officer about the bathroom. The inmate was given an order to enter the rec area so not to cause further attention to the dorm. The inmate refused and struck the Officer in the face with closed right fist. The Officer used body holds and tripped and fell to the floor striking his own head and then attempted to activate his P.A.S. The inmate then began striking him with both fists to the head and face. The Officer continued force against the inmate by striking him with punches to the body while attempting to block the assault against him. The Officer was then able to activate his P.A.S. and the inmate stopped and retreated to his cube. The response team arrived and approximately 30 inmates exited the dorm and entered the rec area and began surrounding and arguing with the response team and refusing to return to their cubes for 5-10 minutes before they eventually complied.