A handicapped person hit me in the gym yesterday.

so…yesterday (on my birthday),  I had just gotten to the gym and was climbing the stairwell to the second floor with my girlfriend,  I think I was futzing with my ipod buds, when from out of nowhere I received a hard punch to the left shoulder.  I immediately spun around and scanned for a buddy, thinking that it was someone saying “Hi” in a high school kinda way, but the punch was really unnecessarily hard for this.  For all my scanning, all i turned up was a stocky, handicapped hispanic dude, all of 5’1″ and 20 years of age. Immediately he was surrounded by 5 female friends/relatives/cousins all of the same disposition yelling, “please sir, he doesn’t know what he’s doing”.  i kept moving ( a class had just gotten out and the flow of traffic was surging me along in my confusion).  After my workout i reported it to the management, hoping it might prevent a future occurrence. Had he hit me in the face i would have gone down hard and had a broken mandible.

What does one do in this situation?