TWO members of staff at a sandwich bar in Preston Road, Wembley, were robbed at gun-point last Thursday.
The 24-year-old and 29-year-old victims, who work at Subway, were about to close the shop when a man walked in and threatened them with a gun at 10.22pm.
The robber demanded cash, before making the men stand at the back of the shop while he escaped. He ran out of the store towards Carlton Avenue East.
The suspect is described as a white man, about 6ft tall, with a large build and between 35 and 40 years old. He was wearing a hi-vis top underneath a khaki coat, black trousers and dark blue adidas trainers.
He was carrying a black and blue backpack over his shoulders and was also wearing a white woollen glove and latex glove, as well as a black balaclava.
The robber also had a distinctive scar on his top lip, which may be a cleft pallet.
Detective Constable John Baker, from Finchley Flying Squad, which investigates armed robberies, said: "This was a deeply traumatic and distressing ordeal for the victims.
"The Flying Squad will work tirelessly to bring these offenders to justice, however, this is only possible with the assistance of the public. "I would urge anyone with information to contact me or Crimestoppers."
Anyone with information can call 020 8358 1751 or Crimestoppers, anonymously, on 0800 555 111.