A police office and a woman have been killed near Parliament in central London in what Scotland Yard are treating as a terrorist incident.
The woman was among several pedestrians struck by a car on Westminster bridge, before it crashed into railings.
An officer was stabbed in the Houses of Parliament by an attacker, who was shot by police.
Police said there were “a number of casualties” and a “full counter-terrorism inquiry” was under way.
Writing on Twitter, BBC home affairs correspondent Dominic Casciani said it is understood from multiple sources that two people were in the vehicle on the bridge.
Prime Minister Theresa May is to chair a meeting of the government’s emergency Cobra committee later.
Met Police Commander BJ Harrington said he was unable to confirm details of casualties.
Speaking outside Scotland Yard he urged the public to stay away from the area around Westminster to allow emergency services access.
London Ambulance said it had treated at least 10 people on Westminster Bridge.
The Port of London Authority said a woman has been pulled alive from the River Thames near the bridge and was being treated for serious injuries.
Junior doctor Colleen Anderson from St Thomas’ Hospital confirmed the death of the woman and said a number of other people were hurt – some with “catastrophic” injuries.
She said she also treated a police officer in his 30s with a head injury, who had been taken to King’s College Hospital.
She said the woman had died at the scene.
“There were people across the bridge. There were some with minor injuries, some catastrophic,” she added.
“Some had injuries they could walk away from or who have life-changing injuries. There were maybe a dozen [injured].”
Source: BBC