A young boy was thrown from a 10th-floor viewing platform at Tate Modern in London on Sunday afternoon, according to the Metropolitan Police Service.

The 6-year-old boy was found a fifth floor platform of the museum alive, and transported to a hospital by helicopter. He is reportedly in critical condition. A 17-year-old male was taken into custody on suspicion of attempted murder in connection with the incident. “There is nothing to suggest that he is known to the victim,” the Metropolitan Police said of the suspect.

Immediately following the incident, Tate Modern locked most of its doors, and asked everyone to remain on its premises. After the police arrived and the victim was evacuated, visitors were allowed to leave, with the museum announcing around 5 p.m. that it would remain shuttered for the remainder of the day. (It is typically open until 6 p.m. on Sundays.)

“Tate is working closely with the police,” the museum said in a statement this evening. “All our thoughts are with the child and his family.”

Tate Modern opened in 2000 in the disused Bankside Power Station along the Thames, a project overseen by the Swiss firm Herzog & de Meuron. In 2016, a 10-story expansion by the same architects, known as the Switch House, opened.

In 2018, more than 5.86 million people visited Tate Modern, making it the most-visited museum in the United Kingdom, after the British Museum.

ARTnews has reached out to Tate Modern. This post will be updated.