London police said on Saturday a number of pedestrians had been injured near the city’s Natural History Museum and that a man had been detained at the scene.

British media reported a car had mounted the pavement outside the tourist attraction.

The crash happened at 2:20 p.m. on a day when the central 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. It was not immediately clear if he was pinned down by police or others at the scene.

Police described the incident in the South Kensington area of west London as a collision and said the motive for the incident was under investigation, but was not being treated as terror.

“Inquiries to establish the circumstances and motive are under way,” police said.

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

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

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 and the same month a van was driven into worshippers near a mosque in north London which left one man dead.

The Associated Press contributed to this report.