Video captures the moment hell broke loose in London

VISION shows the moment a woman plummeted into the River Thames after a terrorist ploughed through crowds on Westminster Bridge.

HORRIFYING vision shows the moment a woman plummeted into the River Thames as a terrorist ploughed through crowds on Westminster Bridge.

Published by the BBC, the grainy video purportedly shows the attacker driving a speeding four wheel drive across the bridge, knocking down pedestrians as the vehicle mounts the pavement.

As the driver speeds across the bridge, a woman is seen to fall from the bridge into the river below after the crazed driver passes her position.

It is unclear whether or not the woman was knocked by the vehicle or knocked to get out of its way.

Authorities have confirmed a woman was later pulled from the water and taken to hospital with serious injuries.

Earlier, witnesses to the fatal Westminster terror attack have captured the moment hell broke loose in the heart of London on video.

Panic broke out outside the UK Houses of Parliament on Wednesday afternoon when a man emerged from an out-of-control car and launched himself at a police officer.

Workers, tourists, parliamentarians and visiting school groups heard gunfire and knew something serious had happened as police officers began evacuating the area.

“Move yourself, go!” a policeman shouted in a video captured by a BBC camera. “Get under cover, get under cover now!”

Car mounts pavement on Westminster bridge. Picture: BBC

The moment a person is seen falling from the bridge and into the river. Picture: BBC

A splash is seen in the water immediately after the figure is seen falling from the bridge. Picture: BBC

Panicked people ran for safety when gunshots were fired.

Video shows the moment hell broke loose in London terror attack.

The attacker charged his vehicle through Westminster before emerging to stab a police officer.

Another chilling clip shows terrified people spilling out of the building’s gates as several gunshots followed the initial bang.

It is now known that one of those shots killed the attacker after he stabbed a police officer at the security checkpoint at the front of the secure building.

The police officer and alleged terrorist are among five people killed in the attack.

The area was quickly locked down. Picture: Jack Taylor/Getty Images

Before the attacker reached Parliament, at least 20 others were injured when he mowed down pedestrians in a car on a nearby bridge.

Westminster Bridge was littered with bodies after the attacker drove into pedestrians, before crashing into the gates outside Parliament.

Of the injured, at least six are in a critical condition sparking fears the death toll may rise.

Police said they were treating the attack “as a terrorist incident until we know otherwise”.

The attacker was shot dead by police. Picture: Stefan Rousseau/PA via AP

Up to 20 people were seriously injured on Westminster Bridge. Picture: Reuters/Toby Melville