The Natural History Museum alone had 4.6m visitors previous year, equivalent to around 12,600 on an average day.
According to The Independent, the Metropolitan Police put out a statement which said: "The man detained by officers is now under arrest and is in custody at a north London police station". London Ambulance Service said 11 people had been hospitalized for their injuries.
'Their injuries are not believed to be life-threatening or life-changing.
Officers detained a man at the scene while officers investigate what had happened.
It is not yet clear if what is being described as an "incident" by police is terrorism related.
In June seven people were killed and over 30 more injured when a van plowed into a group of pedestrians outside of a pub near the London Bridge, before three knife-wielding suspects stabbed several patrons.
"Enquiries have established that this incident is not terrorist related and I'd like to thank those who came to assist the injured".
"A man (no further dets) has been detained at the scene".
The museum is in the busy South Kensington section of London, popular with both Londoners and tourists.
One video online showed a man being restrained on the ground in the middle of Exhibition Road.
The Natural History Museum - the fourth most popular tourist attraction in the United Kingdom, according to industry figures - tweeted after the incident that it was still open for visitors. "He is now in custody at a north London police station, officials said".
Nearby museums including the Science Museum and Victoria and Albert Museum were evacuated with Tube stations sealed off by police.
'If you have any information about this incident, please call 101'.
BBC reports there are armed police and armed response vehicles on the scene.
Security is high in Britain after five terror attacks since March - four of them in London and one in Manchester - with the bloodshed claiming 35 lives.