Police are hunting for four men who stole cash and cigarettes from a shop in Sutton.
Officers were called to the convenience shop on Northwood Avenue at 8.50pm on Saturday.
Four masked men, all wearing dark clothing, had entered the shop and threatened staff with a crow bar.
After gaining access to the safe they loaded a white rubble sack with money and cigarettes before fleeing the scene, possibly in a car.
The staff at the shop were shaken but not injured during the robbery.
Police have now stepped up patrols in the area as part of their investigation.
Det Insp Rich Monk said: “It was only just getting dark at this time so we are appealing for anyone who may have been in the area to think back and consider whether they saw anything out of the ordinary?
“Did you see a car in Northwood Avenue around this time, either before the robbery or just after? Or did you see the robbery take place.
“We will be analysing CCTV and continuing with enquiries but if you have some information that could help our investigation please let us know.”
Anyone with information should contact police on 101 or call Crimestoppers in confidence.