Teen arrested after boy thrown from museum

LONDON — A teenager was arrested on suspicion of attempted murder after a 6-year-old boy was thrown from Tate Modern museum in London on Sunday, the Metropolitan Police said.

The child was tossed from the 10th-floor viewing platform and landed on the fifth-floor roof, the police said. The victim was airlifted to a hospital in critical condition.

The 17-year-old male suspect was arrested by police officers on the same viewing platform.

‘‘There is nothing to suggest that he is known to the victim,’’ the police said.

The episode led to the lockdown of the renowned museum, with some visitors saying on social media that they were trapped inside, and others saying they were turned away.

A police spokeswoman said authorities were called to the museum about 2:45 p.m. The London Ambulance Service and London’s Air Ambulance also responded to the scene. Images and video shared on Twitter showed a helicopter landing outside Turbine Hall and visitors huddled in the museum’s cafe.

Tate Modern is on the south bank of the River Thames, across the Millennium Bridge from St. Paul’s Cathedral in the British capital. It holds galleries of modern and contemporary art in more than 371,000 square feet of space and has been one of the world’s most popular art museums since opening in 2000.

Some people sat on the floor of Turbine Hall waiting to be let out. Others waited in the museum’s coffee shops. The museum’s exhibitions were closed for the rest of the day.

Visitors often flock to the museum’s balcony on Level 10, the top floor, to admire a 360-degree panorama of London. The terrace opened as part of an extension in 2016 and offers views of some of the city’s famous landmarks, including St. Paul’s Cathedral; the Leadenhall Building, a skyscraper better known as the Cheesegrater for its distinctive appearance; and the Houses of Parliament.