Four people have been killed after a knifeman brought terror to the heart of Westminster.

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 armed officers.

The police officer and the attacker were both killed, along with two others on Westminster Bridge.

Eyewitnesses described scenes of terror when gunfire rang out as the attacker approached a second officer within yards of the Houses of Parliament.

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.

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