Police say they have foiled an active terror plot after a woman was shot during a raid on a house in Willesden, north-west London.
The 21-year-old woman was one of the subjects of the investigation and is in a serious but stable condition.
A raid also took place in Kent, with six people arrested in total.
Officers say the operation was not connected to an arrest near Parliament on Thursday, when a man was detained on suspicion of terror offences.
Police said the house in Harlesden Road, Willesden, which was raided on Thursday evening, had been under observation.
At about 19:00 BST, firearms officers entered the property. CS gas was sprayed and a woman was shot.
A 16-year-old boy, and a man and woman, both aged 20, were arrested. A 43-year-old woman was arrested in Kent.
Two further arrests were made in Willesden after a man and woman, both aged 28, returned to the raided property.
The police said the suspects had been arrested on suspicion of the commission, preparation and instigation of terrorist acts.
They are in custody at a south London police station.
Neil Basu, deputy assistant commissioner of the Metropolitan Police, said: “Due to these arrests that have been made yesterday, in both cases I believe that we have contained the threats that they pose.”
When asked by reporters whether police had foiled an active terror plot, Mr Basu replied: “Yes.”
He added: “There are constant acts of immense bravery by officers, armed and unarmed – those that the public see, where our officers run towards danger just as you saw yesterday, but a huge amount of unseen work that the public will never see behind the scenes.”
Alex Paton, 50, who lives in Harlesden Road, said he saw a woman “getting all cuffed up and put in a white suit”.
He described seeing “coppers and masked men with guns”.
Another resident of the area said she had heard the “bang, bang, bang” of shots.
A neighbour of the raided property suggested the shot woman had suffered injuries to her left arm and stomach.
He said the family who lived there were from Somalia.
‘Don’t touch me’
Ruth Haile, who lives in the road, said she heard shots and the woman on the ground shouting: “Don’t touch me, my body, don’t touch my dress.”
Speaking about the shot woman, a police spokesman said: “Due to her condition, she has not been arrested at this time and remains under police guard at hospital.
It is believed to be the first time a woman has been shot by police in 10 years. The last time was in 2007 when Ann Sanderson was fatally shot in Kent.
Police said searches had taken place at “linked addresses”, as well as where the arrests took place.
The Willesden raid has been referred to the Independent Police Complaints Commission and the Met’s directorate of professional standards, as is procedure.
The IPCC said it was gathering evidence but that no officers were under investigation.
On Thursday, police arrested a 27-year-old man at the junction of Parliament Street and Parliament Square, in London, as part of an intelligence-led operation.
He was identified on Friday as Khalid Mohamed Omar Ali, a British national who is believed to have gone to school in Tottenham, north London, but was not born in the UK.
The Met said he had been detained on suspicion of terrorism offences and that knives were recovered from the scene.
He had been on the force’s radar for some time and it is thought police acted after a concerned family member contacted them.
‘Grateful for dedication’
Home Secretary Amber Rudd said she had spoken to the Met about both incidents and thanked them for their actions.
“I would like to reinforce my gratitude to the police and security services, who work tirelessly around the clock to keep the people of this country safe,” she said.
“They carry out their duties with calmness and professionalism, and we are all grateful for their dedication.”