Cellphone footage of the brazen cash-in-transit heist, carried out at Laudium Square, shows how five suspects approached the SBV van and forced the driver and three security guards out of the vehicle.
"They were armed with rifles and pistols," said police spokesperson Lt-Col Katlego Mogale. "It is alleged that one [guard] was pistol-whipped on his head and another sustained injuries to his elbow when he fell down while jumping out of the vehicle."
The robbers made off with an undisclosed amount of cash as well as weapons.
The suspects fled the scene in a silver 2012 model Toyota Hilux with registration number BB 81 HV GP.
SBV said it was working closely with the authorities to investigate the crime and bring the perpetrators to justice.