Dramatic CCTV footage has emerged 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 and obtained by ITV News, shows a number of officers wrestle to the ground the 28-year-old British man, of Azerbaijani origin, outside the Planet Organic store around 7pm last night.Once they've got him down, four cars swoop in.It formed part of an operation to simultaneously detain a group of suspected Islamist terrorists amid fears an attack similar to the Kenyan mall atrocity had been planned on British soil.At the same time as the Westbourne Grove seige, armed police fired special ammunition - designed to breach doors or burst tyres - to stop a car on Mansell Street, near the Tower of London.They also 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.