Three gunshots can be heard at Westminster as bystanders run for cover during the terror attack.

The Metropolitan Police has confirmed four people have died and 20 injured in the attack, which happened at Westminster at around 2.40pm on Wednesday (March 22).

One of the dead is an armed police officer who was stationed outside Westminster.

The suspected attacker is among the fatalities.

Eyewitness footage from the scene captures the moment three gunshots were fired at Westminster.

A black car is seen leaving parliament as people run across the street to flee the scene.

The Met Police said the attack started when a car ran over pedestrians on Westminster Bridge.

An assailant entered Westminster and stabbed and killed a police officer.

Parliament was locked down following the incident, which police soon labelled a terrorist attack.

Prime Minister Theresa May was immediately taken away from the scene in a security convoy.

Police have said they believe a lone man was behind the attack.