The victim was found on a fifth floor roof and treated at the scene by paramedics before being taken to hospital by London's Air Ambulance. The boy's condition is critical; his family are being supported by police. A child fell from height and is being taken to hospital by London's Air Ambulance. There is nothing to suggest that he is known to the victim.
There are unconfirmed reports the child fell from the 10th floor balcony or viewing gallery.
Others wrote that the art gallery had been evacuated, although some people remained inside and the building was "on lockdown".
The Tate Modern in London is now on lockdown after a young boy "fell from a height" this afternoon.
She said the person who was restrained by members of the public before the police arrived "just stood there and was quite calm".
An eye-witness told the Mirror: "I heard the impact and then screaming from above as a woman screamed: 'he's my son!"
A London Ambulance service spokesman said that after they were called at 2:40pm two ambulance crews were sent to the scene, along with the Hazardous Area Response Team and the air ambulance. "Visitors to the gallery have been allowed to leave". We didn't know what condition he was in.
A sign placed outside the gallery confirmed that it would be closed for the rest of Sunday.
The Tate Modern is Britain's top visitor attraction, with 5.87 million visits in 2018, according to the Association of Leading Visitor Attractions.