Video report by ITV News UK Editor Lucy Manning
Detectives have spent the day questioning a group of suspected Islamist terrorists amid fears the men were plotting to launch an attack in Britain.
ITV News obtained dramatic CCTV footage of one of a series of arrests across London, in which counter-terror police are seen tackling a suspect on the upmarket Westbourne Grove in west London.
The black-and-white footage, captured by the 65 & King bar, shows a number of officers wrestle to the ground the 28-year-old man, a British national of Azerbaijani origin, outside the Planet Organic stores around 7pm last night before four cars swoop in.
At the same time, armed police fired special ammunition - designed to breach doors or burst tyres - to stop a car on Mansell Street, near the Tower of London, and arrested two men, both aged 25. One is a British national of Turkish origin, while the other is a British national of Algerian origin.
A 29-year-old, a British national of Pakistani origin, was also held in Peckham Street, south-east London, during last night's MI5-assisted operation.
All the men have been detained on the suspicion of the commission, preparation or instigation of acts of terrorism, Scotland Yard said, and are being quizzed at a south London police station.