A six-year-old boy who was thrown from a 10th-floor viewing platform at the Tate Modern art gallery in London is now in a critical but stable condition, police have said.
Scotland Yard said the child remains in hospital after being found on a fifth-floor roof on Sunday afternoon but is “no longer in a life-threatening situation”.
A 17-year-old boy remains in custody on suspicion of attempted murder, the force added.
Police said there is nothing to suggest the child is known to the teenager, who remained with members of the public on the viewing platform after the incident at around 2.40pm
A spokeswoman for the Tate said Tate Modern will open on Monday as usual but the viewing platform will remain closed.
A photocall for a new exhibition scheduled for Monday morning has been postponed, she added.
Scotland Yard said several members of the public are assisting police with witness statements.
Admin worker Nancy Barnfield, 47, of Rochdale, was at the 10th-floor viewing gallery with a friend and their children when her friend heard a "loud bang".
Ms Barnfield said she then saw a woman screaming: "Where's my son, where's my son?"
Members of the public quickly gathered around a man who was nearby, she said.
Ms Barnfield said: "We did not notice the mum before, we noticed her after because she was hysterical by then."
She said the person who was restrained by members of the public before the police arrived "just stood there and was quite calm".
Another witness, who had been on the fifth floor in the member's lounge, 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."
Officers had been called to the gallery at around 2.40pm and the child was treated at the scene before being flown to hospital by London's Air Ambulance.
Visitors reported on social media not being allowed in or out of the gallery while emergency services dealt with the incident.
A visitor, who did not want to give his name, said they could hear an air ambulance which had landed on the concrete walkway in front of the building.
A group of uniformed police officers could be seen going into one of the gallery entrances at 4.53pm as the metal shutters were brought down and visitors were turned away.
BBC journalist Jonny Dymond, who was in the gallery at the time of the incident, said visitors were funnelled into a main hall while all exits were closed.
He added: "There were quite a lot of families with children, and security guards told us we couldn't leave. There were at least two fire engines, 10 police cars and an incident control unit.
"Parts of the exterior of the building were taped off."
The Tate remained closed for the rest of Sunday.
A spokeswoman for the gallery said: "Tate is working closely with the police to help with their investigations. All our thoughts are with the child and his family."
The Tate Modern was the UK's most popular tourist attraction in 2018 after being visited 5.9 million times, according to the Association of Leading Visitor Attractions.
With the schools having broken up and holiday season begun, there are likely to have been thousands of visitors to the gallery on Sunday.