At least 11 pedestrians have been injured in a car collision outside London's Natural History Museum, in a crash that "is not being treated as a terror-related incident", UK police said.

A man was detained at the scene on Saturday after a vehicle apparently mounted the pavement outside the popular tourist attraction in the South Kensington area of the UK capital.

"The incident is a road traffic investigation and not a terrorist-related incident," London's Metropolitan Police said in a statement later in the day.

The crash happened at 220pm (13:20 GMT) on a day when the west London museum is usually teeming with pedestrians, including international tourists. Photographs showed a dented silver car and a man being pinned to the ground outside the museum.

"We treated 11 patients, mostly for leg and head injuries, and took nine of them to hospital," Peter McKenna, deputy director of operations at the ambulance service, said.

We attended an incident at Cromwell Road, South Kensington this afternoon. Our statement is below. pic.twitter.com/yBdANOXuZH — London Ambulance (@Ldn_Ambulance) October 7, 2017

The museum had earlier said on Twitter it was working with police after "a serious incident" outside and would provide more information later.

Al Jazeera's Neave Barker, reporting from London, said that armed units and forensic teams rushed to the scene after the incident.

Britain is on its second highest security alert level, meaning an attack considered highly likely, and there have been five attacks already this year, three involving a vehicle.

"What we have seen is an incredibly rapid police response," he said.

There is a tremendous amount of sensitivity and concern from the ordinary public," added Barker. "The police here in the capital are most certainly not taking any chances."