"They entered the casino at 23:50 and ordered the cashier to give them money from the till and a small safe... they then fired two shots and fled," spokesperson Wilmarie van der Merwe said.
A security guard barricaded the exit, but the men managed to drive through.
They allegedly shot at another security guard on a motorcycle, wounding him.
The man was in a stable condition in hospital.
"As the men drove off on the Sun City - Pretoria road, other security guards chased after [them].
"The men stopped and opened fire. A shoot-out ensued... and the men fled. No-one was injured in that shoot-out," she said.
Two of the four vehicles allegedly used in the robbery were found abandoned.