Six people including three living just over a mile from the Olympic site and a former police community support officer have been arrested over a suspected terror plot.
Five men and a woman were arrested on suspicion of the commission, preparation or instigation of acts of terrorism and were being held at a south-east London police station, police said.
ITV News' UK Editor Keir Simmons reports:
Three of the suspects were arrested in a dawn raid on a house in Stratford in East London, roughly a mile away from the Olympic stadium. Police said the plot was not linked to the Olympics or the Paralympics.
They are believed to be members of the same Bangladeshi family. One, aged 24, was Tasered during his arrest but did not require hospital treatment, a spokesman for the Metropolitan Police added. The others were aged 18 and 26.
One of the men arrested is understood to be Richard Dart, a British national who converted to Islam in 2009 and has been a prominent critic of the wars in Iraq and Afghanistan.
Neighbours said the occupants of the house in Stratford had been there for more than a year and that there were frequently men in Muslim-style robes coming and going from the property. A blue police tent remains outside he door of the house this evening.
In Ealing, West London, a 29-year-old man was arrested in the street, and a 21-year-old man and a 30-year-old woman were held at separate residential premises.
One of those arrested is a former police community support officer. A spokeswoman for Scotland Yard said: "One of the men arrested by the Counter Terror Command today served as a PCSO for the MPS [Metropolitan Police Service] from May 2007 to September 2009 when he resigned. He was not deployed in any specialist or sensitive roles."
The arrests were part of a pre-planned intelligence-led operation by the Metropolitan Police counter-terror command along with armed officers.
Eight residential premises in East, West and North London and one business premises in East London were searched.
ITV News' UK Editor Keir Simmons said that anti-terrorism officers would have been monitoring the suspects for some time and that it's likely they decided to break their cover to avoid arrests in the days before the Olympics.