Police have surrounded a street in Notting Hill, near Portabello Road and Talbot Road late on Thursday evening.
Armed police can be seen shinning laser target lights in homes through windows and from the rooftops off adjacent buildings.
Local residents who are shell shocked by this Hollywood style incident are hiding not knowing what to to expect, as balaclava-clad officers brandished fully automatic rifles and scoured the area for runaways.
They have also placed themselves strategically on scaffolding whilst officers search for a unknown person.
Police have advised all residents to stay inside their homes as the significant police presence swarm the street.
Witnesses said the main police presence was on Portobello Road, Colville Square, Colville Terrace and Talbot Road.
Details are coming through slowly as this is an ongoing police operation and we will update the story with more information as it breaks.