text: Four officers were injured when the Met's Flying Squad swooped on the men in Piccadilly at 11:25 BST.
  A Taser was discharged several times and the policemen were hurt as the men tried to escape on mopeds.
  Four men have been arrested and are being held at London police stations.
  A Met Police spokesman said three officers suffered minor injuries and the fourth is in hospital in a serious condition.
  Store owner Avi Reed said the gang smashed a glass cabinet, causing more than Â£300,000 of damage,
  Mr Reed said police contacted them at the Chronext store earlier to warn them that there might be a robbery, and the shop was closed to protect customers.
  He said: "At about 11:30 we saw three guys, they had helmets on. One tried to smash the door with a hammer. The glass didn't break as it's protected but he managed to get in.
  "Another guy had an axe and managed to smash a cabinet, while the other stayed on the motorbike. They caused enormous damage."
  Mr Reed praised the actions of the "amazing" police.
  Det Supt Craig Turner, said: "Our officers are absolutely committed to keeping London safe and target the criminals who pose a danger to Londoners and our city businesses day in, day out.
  "They know that this work carries with it very real risks and dangers but take this in their stride as part of serving the public.
  "However, today's events highlight how the reckless behaviour of those determined to evade justice, heedless of the consequences, can have a real impact on all those involved."
  Piccadilly was closed eastbound at Hyde Park Corner for about six hours while investigations were carried out.
target: A moped gang armed with knives and an axe has been intercepted by police in a "terrifying" attempt to rob a luxury watch store in central London.