It was understood he was due to be discharged late yesterday.
"Police are yet to speak to the victim in greater detail, but he has described being assaulted by a group of six young people after chasing them around the back of The Warehouse and confronting them."
Mr Clubb said officers would be looking at CCTV footage in the area to try and identify the attackers.
"There's a nearby gym that opened at 5am and we'd like to speak to anyone who was in the area and saw the security guard or any groups of people behaving suspiciously."
Westgate management said they understood that the guard had just started work.