Gunmen held up a jewellery store in Oxford Street and escaped with more than £500,000 worth of luxury watches in front of terrified shoppers at the height of the rush hour.

Witnesses said unarmed officers confronted the armed raiders at the scene but were forced to withdraw when they were threatened with guns.

Scotland Yard said officers were called to the Watches of Switzerland store at 5.32pm yesterday.

A spokesman said three men with guns entered the store and threatened staff before escaping with bags stuffed with luxury watches.

The men wore hooded tops and had their faces covered. No-one was injured in the raid. The raiders escaped on foot.

One witness said on Twitter: “!There were 3 guys in black one had a gun & was pointing it at people then the other 2 were smashing the...

“windows with hammers & cutting off the watches from the display. Was like a film. Could hear the police coming. Thank God for rapid response.”

She said the scene was like a movie but the raiders got away because the first officers on the scene were unarmed.

She tweeted: “Like the police got there when they were there but allowed them to leave. Why didn’t they bring guns.”

The robbery comes after jewellery and designer stores in the West End were plagued by a series of smash and grab raiders.

However, the use of guns is a worrying escalation in violence in the robberies where criminals have usually used sledgehamers to smash windows and grab items.

The Watches of Switzerland store in Oxford Street has been targeted before by gangs using motorbikes or scotters to escape.

Police today appealed for witnesses to the latest incident to contact them on the non emergency number 101.