- A car had mounted the sidewalk outside museum in South Kensington
- Counter-terror officers haven't reached conclusion on circumstances
- It was said earlier the incident was not treated as terrorism-related
Police said it was believed the car had mounted the pavement outside the popular attraction in west London and collided with a number of pedestrians. Officers had arrested a man at the scene and he was now being questioned.
Britain has suffered five attacks blamed on terrorism so far this year, three of which involved vehicles, and the incident in an area packed with tourists at the weekend had prompted concerns that the collision had been a deliberate act.
"The incident is a road traffic investigation and not a terrorist-related incident," a police statement said.
Unverified footage from the scene showed a man being pinned to the ground by what appeared to be four security guards or police officers.
The Natural History Museum is located on Exhibition Road in South Kensington, one of the British capital's most upmarket districts and home to a host of other museums, restaurants as well as university buildings.
It is the fourth most popular tourist attraction in the United Kingdom, with 4.6 million visits during 2016, according to the Association of Leading Visitor Attractions.
Britain is on its second highest security alert level, meaning an attack by militants is considered highly likely.
In March, a man drove a car into pedestrians on London's Westminster Bridge killing four before stabbing a police officer to death in the grounds of parliament.
Three Islamist militants drove into people on London Bridge in June before stabbing people at nearby restaurants and bars, killing eight. The same month, a van was driven into worshippers near a mosque in north London which left one man dead.
(This story has not been edited by NDTV staff and is auto-generated from a syndicated feed.)
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