The suspects reportedly made off with six R4 rifles and a magazine with 10 rounds of 5.56mm ammunition from the Ninth South African Infantry Battalion base.
The robbers reportedly forced the guards inside the base and overpowered another five soldiers in an armoury guard room.
The guards were forced to open a weapons safe.
South African Police Services spokeswoman Noloyiso Rwexana said the SAPS could not comment or confirm the incident and referred the matter to the South African National Defence Force.
SANDF spokesperson Brigadier-General Mafi Mgobozi confirmed the robbery and said the SANDF was investigating.
“Our members are still on the scene and once all information has been made available a statement will be issued,” he said.
In an unrelated case earlier this year, Duncan Gouvias 22 pleaded guilty in the Wynberg Regional Court to five charges of burglary and contraventions of the Firearms Control Act.
His sentences totalled 43 years but will run concurrently.
Gouvias, Dilian Sewkumar 18 and Karabo Ramokgopa 19, sons of navy personnel, admitted stealing automatic weapons hand grenades and ammunition from Simon’s Town naval base in August last year.