A woman has died on Westminster Bridge in central London in what police are treating as a terrorist incident.
A police officer was also stabbed in the nearby Houses of Parliament by an attacker, who was shot by police.
Several pedestrians were struck by a car on the bridge, before it crashed into railings.
Police said there were “a number of casualties… including police officers” and a “full counter-terrorism inquiry” was under way.
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.
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].”