A shopkeeper was pistol-whipped in Gloucester Road, South Kensington, when three raiders robbed the Ross Foods shop at gunpoint.
The 51-year-old had been looking after the till at family-run Ross Foods in South Kensington for just a few minutes while the owner went downstairs on Friday at 9.30pm.
Two robbers stormed into the shop wearing balaclavas and holding handguns.
One of them demanded: "Give me the money," and went behind the shop counter pointing his gun at the victim, Mr Malik.
The raider struck the 51-year-old on the head with the weapon, opening a one-inch gash on the man's left eyebrow.
The bleeding victim then opened the till for his attacker who took between £500-£600 pounds before leaving the shop with his accomplice.
Police were alerted to the armed raid when a witness came out of a restaurant nearby to tell officers that a shopkeeper had been assaulted.
An ambulance was called which took a 'visibly shaking and disorientated' Mr Malik to Chelsea and Westminster Hospital in Fulham Road, Chelsea.
Officer on the case DC Brad Weston of Barnes Flying Squad said: "In the attack, violence was used that wasn't needed. Threatening someone with a gun is frightening enough."
The victim's nephew, Osman Malik, who works at the shop which his parents own, said that his uncle is recovering after his ordeal.
"He was shaken up after it happened," he said. "My mum had only gone downstairs for a second and he was looking after the till for her."
DC Brad Weston added that the punishment for the criminals who committed this robbery could be 'quite a substantial sentence.'
"A serious robbery means serious time," he added.
The attacker was described as black, 6ft, aged 18-25 wearing a dark grey hooded top with a zipped front and the hood up and a thick black cotton balaclava.
The other raider was black, aged between 15-18 wearing a dark grey hooded top with detail across the chest and with his hood up.
Call DC Weston at Barnes Flying Squad on 020 8247 7948 or Crimestoppers on 0800 555 111 with any information about the robbery.