From the BBC. Good pictures at ITV News

Five men and a woman suspected of terrorism offences have been arrested in London as part of an intelligence-led investigation involving MI5.

One of the six, who are aged between 18 and 30, was Tasered by police. Eight homes in west, east and north London and one business have been searched. It is understood the arrests relate to a possible plot involving Islamist extremists, with potential UK targets.

Three of those held are brothers - one an ex-police community support officer. He served with the Metropolitan Police for more than two years before resigning in September 2009. The brothers, aged 18, 24 and 26, were detained in Abbey Road, in Stratford, east London, during an operation involving armed officers. The BBC understands they are Jahangir, Mohammed and Moybur Alom.

Richard Dart, a Muslim convert who uses the name Salahuddin al Britani, was also detained in the raids, it is understood. He features in a YouTube video which criticises the Royal Family and British military action in Muslim countries. People were wondering where Richard Dart was - as he was too quiet, not stalking u pand down with the usual suspects and probably up to no good? Now we know; he was up to no good.

Some - if not all - of those arrested on suspicion of the commission, preparation or instigation of acts of terrorism are British nationals, BBC home affairs correspondent Danny Shaw says.

They include a 21-year-old man and a 30-year-old woman, who were detained at separate addresses in Ealing, west London, while a 29-year-old man was arrested in an Ealing street. The woman is married to one of the men. All six have been taken to a police station in south-east London.

The 24-year-old man who was Tasered during his arrest in Stratford did not need hospital treatment, police said.

The Metropolitan Police said the arrests were not linked to the Olympics or Paralympic Games.