Flying squad officers arrested two men in the process of carrying out a robbery at William Hill bookmakers in Dunton Road on Friday morning.
The incident occurred at around 10.15am. The men had robbed the shop at gunpoint, pointing guns at staff. No shots were fired and nobody was injured.
Flying Squad officers from Tower Bridge intervened as the two robbers tried to leave.
They are a 40 year old man of no fixed address and a 40 year old man from the Camberwell area were arrested and taken to a south London police station.
DCI Keith Butler said it is possible the men were connected to a string of armed robberies at bookmakers in south London, particularly Southwark.
He said: "This is an excellent example of an intelligence led operation with specialist units in the MPS working with colleagues in Southwark Borough Police and Southwark Council.
"We were in a position to arrest these individuals, making Southwark and London safer for us all,"
Anyone with any information about armed robberies should ring the Flying Squad on 020 7232 6530 or Crimestoppers on 0800 555 111 if you wish to remain anonymous.