UPDATED 9.03AM: A taxi driver sparked a major terror alert when his car ploughed into pedestrians in the heart of one of London's busiest tourist areas, leaving 11 people injured.

People fled for their lives after the black Toyota Prius mounted the pavement close to the Natural History Museum in South Kensington on Saturday afternoon.

Video footage posted on Twitter showed a man being restrained on the ground by members of the public after the incident in the heart of the capital's museums district, an area popular with families with young children.

But police later confirmed the incident was "not being treated as a terror- related incident" and a man had been arrested over a traffic collision.

Those hurt were mostly suffering from head or leg injuries, the London Ambulance Service said, with nine taken to hospital. None were in a life-threatening condition.

Pictures and footage from the scene in Exhibition Road showed street damage and a massive police presence in the upmarket area, home to the museum, the Science Museum and the Victoria and Albert Museum (V&A).

Some showed the black Toyota Prius, registered with Transport for London (TfL) as a mini cab, that had collided with a silver Vauxhall saloon and a Jaguar.

Sophie Parry and Lesley Guinness were on their way to the V&A's Pink Floyd exhibition when they saw the driver of a black vehicle swerve across the road and hit a cyclist.

Parry said: "I thought maybe someone might have had a heart attack behind the wheel.

"Because I thought, this is strange for a vehicle - it must have been going pretty slow there to career across and do all that damage.

The friends said they saw people running away from the scene, after three "gunshot-like" bangs rang out a few seconds before the cyclist was struck.

Merilin Mueller, who works in a nearby cafe said police made her evacuate .

"It just seemed like an accident because there was a police car. We couldn't see outside.

"Then there were loads of police cars and that's when all of these police came marching down saying, 'move, move'.

Downing Street had said that Prime Minister Theresa May was being kept up to date with developments.

Later on Twitter, she said: "My thanks to the first responders at this incident this afternoon and the actions of members of the public. My thoughts are with the injured."