A suspected armed robber was caught just moments after a gang hit the Somerset West post office on Tuesday morning.
Western Cape police said two armed men entered the building in Church Street around 09:25 and demanded money from the safe.
They fled with an undisclosed amount cash in the in a black Mercedes-Benz compressor, said spokesperson Captain FC van Wyk.
Police officers managed to stop the vehicle on Baden Powell Road and arrested one of the men.
"Two suspects fled on foot and are being sought," said Van Wyk.
Van Wyk said the getaway vehicle was found to have been reported as hijacked in the Kwanobuhle area in August.
An employee at a nearby shop said on Tuesday that he had been scared when he saw two or three armed men rushing away from the scene with money.
Gordon's Bay Security chief operational officer Heyns de Waal told News24 that they had responded along with other security companies to a police call of an armed robbery in progress, which included descriptions of the suspects.
They then passed on these details to their armed response vehicles.
"Two suspects ran on foot in the direction of the railway line and one drove away in a getaway vehicle, a black Mercedes," he said.
"One of my vehicles immediately picked up the vehicle on the N2 and followed him."
De Waal said they liased with the SAPS flying squad and dog unit, who set up a block on the road along with police from Macassar.
"We boxed him in and cornered him at Baden Powell," he said, adding that other security companies arrived at the scene to assist.
Exactly a month ago, armed robbers targeted three Cape Town post offices on the same day.
Money was robbed from the post offices in Kenilworth, Kuilsriver and Hout Bay.
This, as social grant beneficiaries had queued to collect their monthly payments.
News24 reported that the South African Post Office had started piloting cash payments at various cash paypoints in Gauteng, the Western Cape, the Free State and the Northern Cape, and would continue to do so in other provinces.
"It is a difficult task, but it is being done," said Telecommunications and Postal Services Minister Siyabonga Cwele at the time.
Security, especially, was being prioritised, especially regarding cash payments, the minister said.
"After October, all our systems will be fully optimised. We will continue to pay grants to our recipients without disruptions."