A man has been shot by police and a number of people have been stabbed in an attack on London Bridge which is being treated as “terror-related”.
The Met Police said officers were called to a stabbing at premises near the bridge in central London just before 14:00 GMT.
Videos on social media appear to show several people surrounding a man on the floor who then disperse before the man is shot by an armed police officer.
Another man in a suit and jacket could be seen running from him, having apparently retrieved a large knife.
A separate video has also emerged showing police officers aiming guns at a white lorry that jack-knifed across the bridge.
The footage shows several officers surrounding the vehicle before moving to the rear to check its container.
Whitehall officials have told BBC Security Correspondent Frank Gardner the police action was not intelligence-led and was spontaneous and reactive.
What have police said?
Scotland Yard has tweeted to say officers are “responding to this incident as though it is terror-related”.
“One man has been shot by police. We will provide further information when possible,” the force added.
Earlier, the Met said it had detained a man and said a number of people were believed to have been injured.
London Ambulance Service has declared a “major incident” and have a number of crews at the scene.
Where did it happen?
The stabbing happened on the north side of London Bridge, opposite Adelaide House.
British Transport Police said London Bridge station was currently closed and no trains would be stopping there.
A number of buildings near the bridge, including King’s College London and the News UK building opposite the Shard have been put into lockdown amid the ongoing evacuation of the area.
What did witnesses see?
BBC reporter John McManus said he saw a group of men involved in a fight on the bridge. Police then arrived and shots were fired, he said.
Witnesses described armed police arriving at the scene and shooting a man. Others said they saw a man on the ground, holding a knife.
Amanda Hunter said she was on a bus on the bridge when she looked out the window and saw “three police officers going over to a man”.
“Then one of the police officers shot him,” she said. “It appeared there was something in his hand, she said, but couldn’t be certain what it was.”
Luke Redman, 25, said he heard “12 or 15 (gunshots) in about 10 seconds” as he left the Monument pub and ran down an alleyway to escape.
Noa Bodner, who works in a restaurant on London Bridge, said staff and customers were moved away from doors and windows.
“There was a rush of people coming in, and then everybody basically dived under the table,” she said.