Latest updates: Fatalities following Westminster terror attack

At the time of writing, there are reports of four confirmed deaths including a woman on Westminster Bridge who is believed to have been struck by a vehicle that ploughed into crowds, and a police officer who was stabbed outside the Houses of Parliament.

Witness accounts reported that two people were seen lying on the ground and some indicating that shots have been fired.

Tom Peck, political editor for the Independent, tweeted: "There was a loud bang. Screams. Commotion. Then the sound of gunshots. Armed police everywhere."

The Royal Editor at ITV Chris Ship has tweeted that a woman was pulled alive from the River Thames.

It has been confirmed that Prime Minister Theresa May is unharmed and was not involved in the incident.

The Metropolitan Police have confirmed they are currently treating this as a terrorist incident until they know otherwise.

The following statement has also been released:

The London Ambulance Service have released a statement confirming they have treated at least ten patients on Westminster Bridge and have put a number of hospitals on alert.

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