Police said the Co-op store on Manor Park was broken into around 12.50am on Tuesday.
An eyewitness said the gang all wore jumpsuits and face masks.
He said one wore an '˜anonymous mask' and they used crowbards to break in through the store's entrance.
They then stole meat, dog food and cigarettes before escaping in a white Volkswagen car.
Police said officers were currently reviewing CCTV footage.
Anyone with any information should call police on 101 or Crimestoppers, anonymously, on 0800 555111.