A stabbing attack on London Bridge is being treated by police as “terror related”, the Met has said.
The police said they were called to a stabbing just before 14:00.
A number of people are believed to have been injured and one man has been shot by police, the force said.
Earlier, BBC reporter John McManus said he saw a fight on the bridge, with several men attacking one man. Police then arrived quickly and a number of shots were fired at the man, he said.
The Met said the circumstances surrounding the incident remained unclear but it was treating it as terror-related as a “precaution”.
Earlier, the force said it had detained a man. London Ambulance Service has declared a “major incident”.
British Transport Police said London Bridge station was currently closed and no trains would be stopping there.
Police have advised people near the scene to follow directions from officers on the ground.
The prime minister tweeted he was being updated on the incident and wanted to thank police and all emergency services for their response.