Van der Merwe substation at Elandshoek just outside Rayton was targeted and stripped last week.
The armed suspects, one of whom carried an R5 rifle, overpowered security guards who responded to the incident.
The guards were shot through the legs and tied up.
They were held hostage while the suspects also stole the wheels off their security vehicle.
The wounded guards were found the next morning, still tied up.
Paramedics and the police were summoned to the scene.