Military explosive devices and ammunition were found under a bridge in the Modder River near Glen, outside Bloemfontein, during routine police diving exercise, Free State police said on Thursday.
Police spokesperson Rulene Kuhn said divers found 10 explosive devices, nine rounds and four empty cartridges in the water.
Officers from the Explosive Unit were called in to make sure the mortars were deactivated.
The Inland Water Policing Unit had been searching the water for stolen goods and dangerous objects before the start of the festive season.
“This was done as part of crime prevention duties for the festive season,” said Kuhn.
The area near the steel-framed bridge was known as a dumping area for unwanted stolen objects, she said.
The explosives were found at 9.30am on Wednesday. Kuhn said the source of the explosives was unknown at this stage.
The divers would continue to search the area to ensure there were no more explosives in the water, she said.—Sapa.