A six-year-old boy is in hospital fighting for his life after falling from a tenth-floor viewing platform at London's Tate Modern art gallery.
Witnesses said that a woman shouted 'he's my son' after the boy was allegedly pushed by a teenager.
The gallery went into lockdown at around 3pm (GMT) on Sunday and closed all entrances and exits following the incident at 2:40pm.
Police have arrested a 17 year old boy on suspicion on attempted murder and the injured boy was flown by air ambulance to hospital.
There's been no suggestion that the boys were known to each other.
The incident unfolded on the tenth floor of the iconic Blavatnik Building and the boy is said to have fallen to a fifth floor roof. The tenth-floor viewing platform offers 360-degree views of London.
An eye-witness, who'd been sat in a members' lounge five floors below the platform, told The Mirror: 'I heard the impact and then screaming from above as a woman screamed "He's my son! He's my son!"
'I went inside because the screaming was horrific, the boy didn't make any noise but the people from the viewing platform were screaming.'
People tweeted on social media that they were stuck inside the building after no one was allowed inside or out.
'The Tate Modern is currently in lockdown,' a spokesperson for the gallery told the MailOnline. 'Visitors are not being allowed in or out of the building.'
A spokesperson for the Metropolitan Police said: 'Officers are in vicinity of Tate Modern following an incident this afternoon.
'A child fell from height and is being taken to hospital by London's Air Ambulance. We await an update on his condition.'
