Two armed men entered the post office in Paradys Street just after noon while a third kept a look-out outside.
According to Brackenfell police spokeswoman Captain Erica Crous, one robber pointed his gun at a teller, jumped over the counter and went to the back office.
“He then pointed his gun at a supervisor, while ordering her to open the safe and all the money was taken,” said Captain Crous.
The second robber demanded all the money in the front tills.
No shots were fired and no one was injured.
The three robbers fled in a white Bantam bakkie. They are still at large.
It’s not yet known how much money they took.
Calls to the post office went unanswered on Monday.
SA Post Office spokeswoman Martie Gilchrist said the post office would remain closed until further notice and the public was advised to use surrounding post offices, including the Kraaifontein branch.
“The staff was severely traumatised and are receiving counselling,” she said.