- Man shot by police as he tries to access Palace of Westminster
- Attacker mowed down up to a dozen pedestrians on bridge
- Five dead, including police officer and attacker
- Woman pulled injured but alive from Thames
A police officer is among five people dead after a knifeman brought terror to the heart of Westminster in London.
The attacker, armed with two large knives, mowed down pedestrians with his car on Westminster Bridge, including schoolchildren, then rushed at the gates in front of the Houses of Parliament, stabbing a policeman before he was shot by officers.
The Daily Mail is reporting that the suspect was said to have been an Asian man in his 40s.
The man allegedly drove a year-old Hyundai i40 - worth up to £28,000 (NZ$49, 493) down Westminster Bridge at 'high speed'.
He is believed to have been the only attacker.
Witnesses described scenes of terror when gunfire rang out as the attacker approached a second officer within yards of the Houses of Parliament.
More than 12 people are said to have been hit by a vehicle on the bridge after a 4x4 drove into pedestrians and cyclists before crashing into the gates of Parliament then running through the gates and stabbing the officer. The attacker was shot.
Witnesses reported at least two bodies on the ground on Westminster Bridge and "one in the water". St Thomas' Hospital confirmed one woman has died and a number of others have been hurt - including some with "catastrophic" injuries.
The suspected attacker was pictured being treated by paramedics on a stretcher, as two knives used in the assault lay on the ground nearby.
Paramedics fought to save his life and that of his police victim on the floor of the cobbled courtyard in front of Parliament, with Foreign Office minister Tobias Ellwood among those who rushed to help.
The police officer was wheeled away on a stretcher with his face covered and sources later confirmed he had died.
Paramedics tended to the victims on the bridge and at the gate.
Prime Minister Theresa May was seen being ushered into a silver Jaguar in the grounds of the palace as what sounded like gunfire rang out about 2.45pm.
Sirens were heard rushing towards the scene from nearby Victoria Station.
Footage later emerged of the moment police open fire after the attacker ran through the gates of the Palace of Westminster.
The attack left a trail of destruction on the bridge and at the gate.
Witnesses said the attacker was shot by police as he approached a second officer clutching his knife.
Two people were seen lying within Old Palace Yard, immediately outside Westminster Hall and were believed to be the attacker and the stabbed police officer. The sitting in the House of Commons was suspended while police officers sealed off the area.
Immediately before the attack, a crowd of people was seen running from the direction of Westminster Bridge and around the corner into Parliament Square.
Witness Rick Longley told the Press Association that he saw a man stab the policeman outside Britain's Parliament.
"We were just walking up to the station and there was a loud bang and a guy, someone, crashed a car and took some pedestrians out," he said.
"They were just laying there and then the whole crowd just surged around the corner by the gates just opposite Big Ben.
"A guy came past my right shoulder with a big knife and just started plunging it into the policeman."
Daily Mail political editor Jason Groves said he witnessed the scene from his office window and described the moment the assailant was shot.
"A guy comes through the vehicle entrance wielding something, towards a copper, the copper tumbles," he said.
"The man's running towards Westminster Hall, and then a plainclothes copper comes running out.
"Not from the gate, but from the inside, shoots him once from maybe 10 or 15 yards away with a handgun, and then gets closer to him and shoots him again from over him and he doesn't get up."
Commons Leader David Lidington told MPs a "police officer has been stabbed" and the "alleged assailant was shot by armed police" following a "serious" incident within the parliamentary estate.
Press Association reporter Laura Harding, who was in Westminster at the time of the attack, said: "Everyone has been evacuated into Central Lobby, including a group of schoolchildren and kitchen staff.
"Around 15 schoolchildren aged around 10, with armed police coming through the lobby now.
"The children are really calm, the teachers are comforting them."