BBC NEWS - A woman in her 20s has been shot by police and four people arrested in an anti-terror operation in north-west London and Kent, Scotland Yard says.
Officers say the operation was not connected to the earlier arrest of a man near Parliament.
The woman in her 20s was one of the subjects of the investigation and is in a serious but stable condition.
Two men, 20 and 16, and a woman, 20, were held after the Willesden shooting and a woman, 43, was arrested in Kent.
The Metropolitan Police said they were arrested on suspicion of the commission, preparation and instigation of terrorist acts.
They are in custody at a south London police station.
The woman was shot after armed officers entered an address in Harlesden Road, Willesden, shortly before 19:00 BST on Thursday.
A police spokesman said she was taken to hospital by ambulance.
"Due to her condition, she has not been arrested at this time and remains under police guard at hospital," he said.
"The address and persons connected with it had been under observation by counter-terrorism officers as part of an ongoing intelligence-led operation."
Police said searches took place at "linked addresses", as well as where the arrests took place.
The incident has been referred to the Independent Police Complaints Commission and the Met's Directorate of Professional Standards, as is procedure.
Meanwhile, a video been taken at the moment of shooting has been posted on social media.It shows armed police surrounding a terraced house as five shots rang out.
The arrests came after a 27-year-old man was held by armed officers under the Terrorism Act in Westminster on Thursday afternoon. Police said the two incidents were not connected.