Westminster attack: here's what we know so far

A 'knife wielding man' was shot dead after at least twelve people were mowed down by a car on Westminster Bridge

Update:

Four people have died with many others sustaining 'catastrophic injuries' following what is being called a terrorist attack in central London yesterday.

At least twelve people were mowed down by a car on Westminster Bridge at around 2:40pm yesterday, before the vehicle crashed into railings, and the 'knife wielding man' broke into the grounds of the houses of Parliament where he was shot by armed police, amid reports of an explosion.

The intruder, reportedly armed with two knives, stabbed 48-year-old PC Keith Palmer, the police officer on guard in the grounds of Parliament, who later died after sustaining multiple stab wounds.

The other victim to be identified is 43-year-old Aysha Frade, one of the pedestrians to be mowed down by the 4x4 car on Westminster bridge.

As many as 40 people are said to have been injured in the attack, with one woman pulled alive from the River Thames, now in critical condition, according to reports by Sky News.

Emergency teams were at the scene with an onlooker reporting that she saw over 15 ambulances.

The attacker was shot by police at the scene and later died, with police confirming that seven people have been arrested in relation to the attack.

Prime Minister Theresa May was reportedly evacuated and driven quickly from the scene, bundled into a car by a plain-clothed police man, whilst staff were told to stay inside, with MPs ordered to wait inside the Commons chamber. Parliament has resumed as normal today, with a minute's silence held for the London terror attack victims.

There will be a candlelit vigil tonight in Trafalgar Square, with Mayor of London Sadiq Khan announcing:

'The mayor is asking everyone to come together in solidarity to remember those who have lost their lives, to express sympathy with their families and loved ones and to show the world that we are more committed than ever to the values that we hold dear – that we remain united and open. London is the greatest city in the world. We will never be cowed by terrorism. We stand together, in the face of those who seek to harm us and destroy our way of life. We always have, and we always will.'

We will continue to update you.