Six men were arrested in Cape Town on Wednesday, and illegal weapons and explosives confiscated, Western Cape police said.
Spokesperson Captain FC van Wyk said police were conducting search operations with a focus on illegal firearms and drugs when they made the arrests.
"While they were in Duma Nokhwe Street in Samora Machel, they came across three VW Polos, one with four occupants, the second one with two and the third was empty.
"The occupants were searched and the vehicles tested, but had not been reported stolen," van Wyk said.
"But when police members searched the boots of vehicles, they recovered three explosive devices, including a shock tube used at mines and also used to blow up ATMs.
"The six suspects were arrested and the devices and vehicles were confiscated."
He said the men, aged between 24 and 34, are expected to appear in court soon for the possession of explosives.