Armed police officers were deployed, with enquiries to establish the circumstances and motive undertaken.
The 11 people treated were mostly suffering from head or leg injuries, the London Ambulance Service said, with nine taken to hospital.
A large police presence descended on Exhibition Road, South Kensington, yesterday afternoon after a black Toyota Prius hit people outside the museum at about 2.20pm.
Marilin Mueller, 20, said she thought at first it was a traffic accident but had doubts when "loads of police cars" arrived. Police originally said a man was arrested at the scene but later clarified he had only been detained.More news: Iowa State QB Park takes leave from team for medical reasons
The Natural History Museum tweeted: "There's been a serious incident outside the Museum".
The woman, who did not want to give his name, said: "When everything died down a bit, we went back to the place where he was, and saw that on the ground lay a man, whom the police hold".
Video footage posted on Twitter showed a man being restrained on the ground by members of the public in an area popular with families with young children.
A spokesman for the London police force later said that counter-terrorism officers were assessing the incident but had not yet reached a conclusion, but police are keeping an open mind as to whether it is terrorism-related.More news: India failed to cause problems for opponents, says coach Matos
British media reported a vehicle had mounted the sidewalk outside the tourist attraction. Police said none of the injuries were believed to be life-threatening.
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.
Sky News said the police response to the incident was similar to that of the London Bridge terror attack in June, during which eight people were killed when a van drove into pedestrians and three men went on a stabbing spree.
Panicky scenes ensued after the pedestrians were struck and it took almost four hours for police to reassure the anxious public that it was not another terrorist attack.More news: ICE Director: Arrests Coming To California Neighborhoods, Workplaces
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