Counter-terror police have arrested four men in connection with an alleged Islamist terror plot following raids across west London and in the Thames Valley.
The arrests came ahead of this weekend's Remembrance Sunday and Armistice Day events.
Earlier this month, senior police officers and MPs said there was likely to be a significant rise in the number of armed police at Sunday's commemorations in London due to increased fears of a terror attack.
A 27-year-old man was arrested at gunpoint in a car in the street in Southall, west London.
Two other suspects, aged 22 and 25, were detained at addresses in Hounslow and Uxbridge, also in the west of the capital.
The fourth man, 19, was detained at an address in High Wycombe, Buckinghamshire.
Armed police took part in the operations in Southall, Hounslow and High Wycombe but no shots were fired.
The arrests were made on Thursday evening and in the early hours of Friday.
Counter-terrorism officers were leading searches of various properties in Hounslow, High Wycombe, Uxbridge, Southall, Greenford and Hayes.
The properties include a terraced house on Desborough Avenue in High Wycombe, Sky's Tom Parmenter reported from the scene.
Parmenter said there was some concern in the community over the arrest of the man in the town and the alleged "disproportionate" use of force by anti-terror police.
Youth worker Saqib Deshmukh, who knows the suspect, told Sky News: "One of the concerns that we heard was that it was a disproportionate use of force and armed response. Did it necessitate that? Was there a need for that to happen?
"Was there an actual threat on the ground? And that's a concern - that the actual number of forces and the level of force used is disproportionate and it doesn't merit it based on the evidence."
Local shopkeeper Sutha Tangaraj works opposite the house and told Sky News he saw the armed police arrive.
"At about 7pm or 7:30pm at least half a dozen armed police surrounded the house, they knocked the door and no one answered.
"A lady in the house eventually opened the door and they went and have since been searching ever since."
He said police were at the same address six months ago.
Mr Tangaraj said the man who lives at the property "is a regular customer and lives in the house with his family - his mother is very chatty".
The four men were all taken to police stations in central London.
Scotland Yard said the arrests and subsequent searches were part of an "ongoing investigation into Islamist-related terrorism".
Sky's home affairs editor Mark White said: "Scotland Yard are officially giving very little in the way of information on these arrests, but sources are suggesting it is linked to an alleged extremist plot against the UK."
The arrests came a few months after the national terror threat level in the UK was raised from substantial to severe, meaning a terrorist attack is "highly likely".
