Two men reportedly struck at the McColl’s store on Margetson Crescent in Parson Cross, where they ordered the three employees inside to open the till.
They were said to have been carrying a gun and knife, which they used to make threats.
They left the store with cash and cigarettes, heading towards Remington Road.
Nobody was injured during the robbery, which happened on Tuesday at around 9.20pm.
Detectives are still hunting the culprits, and anyone with information is asked to call police on 101, quoting incident number 923 of April 2. You can also speak to Crimestoppers, anonymously, on 0800 555 111.