Reality TV star Spencer Matthews was forced to hide in the vault of a luxury watch shop as armed robbers smashed their way into the store.
The 30-year-old was in The Hour House, in Duke Street in London's West End on Tuesday as the gang took sledgehammers to shop cabinets.
Eyewitnesses said around six masked men on four mopeds targeted the shop, with one brandishing a machete at members of the public outside.
The thieves rammed the front door with a scooter, before smashing at an inner door with sledgehammers.
Dramatic video also shows the group breaking into the Marlybone store as a woman screams off camera.
One of the raiders gives chase to the person filming before the thugs make their getaway.
Thames Valley fire service engineer Paul Starck was left with glass in his eye after the knifeman tried to smash his car window to stop him calling the police.
In a post on Instagram Matthews said: "I just had to hide in a safe.
"More like a vault downstairs while this watch shop The Hour House on Duke Street got smashed to pieces by armed robbers."
He posted pictures on the social media site of the glass-strewn shop and smashed cabinets.
The socialite said: "These guys drive a scooter through the glass and start battering the shop with hammers, big huge hammers, wearing helmets.
"We're in the back of the shop looking at them, sprint downstairs, hide in the vault until all the noise passes. Come upstairs and the place is just battered. Like I mean Gonzo. All the watches gone."
He and his friends began looking for the "vintage piece" that Matthews had been hoping to collect.
The 30-year-old former Made In Chelsea star went on: "We were looking around and I'm just thinking f****** hell the thing that I've been waiting for has obviously just been nicked so I'm going to have to go and get another one.
"Lo and behold we look around and on the floor amongst all the rubble and the glass and stuff there's one watch in the entire shop and it's mine. Now if that's not luck I don't know what is."
Mr Starck, 43, from Sandhurst, said he had never felt fear like that experienced when one of the men attacked his van window with a machete.
He was driving near to the shop when the group did a U-turn on the road close to him, prompting him to call the police.
"He was trying to get through the window at me because he knew I was on the phone to police," he said.
"I've never been so scared in my life. He had no care in the world, the chap."
He was treated by an ambulance crew after getting glass in his eye.
The Metropolitan Police Twitter account for Westminster @MPSWestminster said that officers were called at around 10.32am on Tuesday.
A series of tweets read: "A number of males armed with weapons are reported to have driven to the premises on mopeds and smashed a window before stealing goods and fleeing.
"Officers attended, including specialist firearms colleagues.
"A man aged in his 30s has been treated by LAS for an eye injury sustained after the shop window was smashed.
"At this stage there have been no arrests."
