The security guard was on duty at 11.30pm, at a business in Fulcrum when he was attacked by a man.
Captain Johannes Ramphora, spokesman for the Springs police, believes it is during the attack that a shot was fired that caused the injury to the security guard.
He was shot in the stomach and was rushed to a nearby hospital.
It is believed the aim of the attack was to rob the building and that more than one robber was present.
Ramphora says the robbers were allegedly disturbed because the security guard pressed the security button.
No arrests have been made.
Anyone with information can contact the Springs police on 011 365 5719/20.
