The police are searching for about 15 people suspected to be involved in a cash-in-transit robbery on Paul Kruger Street in Wonderboom, Pretoria, on Tuesday.
National police spokesperson Col Athlenda Mathe said a Mercedes-Benz SUV rammed into the cash van, causing it to stop, at about 7.50am.
Three G4S security officials were forced out of the vehicle and had their service pistols taken.
"The suspects then attacked the cash van with explosives, causing it to explode," Mathe said.
The Mercedes SUV also burst into flames.