Smash and grab robbers hurled stolen watches worth tens of thousands of pounds at police today as they were chased from the scene of a £500,000 raid.
Officers were called to the Bentall Centre, Kingston, south-west London, in the early hours of today after the alarm was raised.
They found a gang of men armed with sledgehammers had smashed their way inside through glass panel doors in Fife Road, beside Starbucks.
An overnight security guard was threatened by the gang as they targeted a branch of Fraser Hart jewellers.
A large glass panel was smashed and the thieves grabbed handfuls of watches before escaping on mopeds.
Fraser Hart stocks watches manufactured by Rolex, Cartier, Breitling, Bulgari, Gucci and Chanel.
As officers raced to the scene, CCTV operators spotted several suspects heading down Dolphin Street at high speed.
Several officers pursued the suspects, assisted by a police helicopter, and were pelted with stolen watches.
Two men were eventually arrested in Sandy Lane, Sutton, after the moped crashed. Two others were arrested in Cecil Road, Wimbledon, several hours later.
Police believe the men may be linked to a larger criminal gang responsible for series of similar raids across the capital.
Thieves dubbed "Fagin's kitchen" gangs, because they often include teenagers controlled by an older crime boss, have plagued police and retailers.
Wearing helmets and armed with heavy tools they use mopeds to ride close to shop windows and escape quickly through often heavy traffic.
Goods worth more than £4 million have been taken as thieves targeted Watches of Switzerland, Cartier, Dolce & Gabbana and Tiffany and Co.
In May, thieves made off with jewellery worth around £1 million from the Westfield centre in Shepherd's Bush, west London.
Sledgehammers were used to break into the complex and branches of De Beers and Tiffany & Co.
Detective Constable Ron Harvey, of the Kingston burglary squad, said a large quantity of watches were recovered.
He said: "This was an excellent team Metropolitan Police effort greatly assisted by the CCTV operators and members of the public."
Four men aged 21,26, 32 and 23 were being questioned today at Kingston Police Station.