A 6-year-old boy was thrown from the 10th floor of London’s Tate Modern art gallery Sunday — leading to the arrest of a teenager on suspicion of attempted murder, police said.

The child landed on the fifth floor of the world-famous art museum after being hurled from a viewing platform around 2:40 p.m local time. He was airlifted to a hospital in critical condition.

His mother “screamed ‘My son, my son,’ ” witness Nancy Barnfield, 47, told The Telegraph.

“She sounded terrified.”

Another witness told the Mirror they heard the distraught mom yell: “He’s my son! He’s my son!”

“I went inside because the screaming was horrific,” said the witness, who was not named. “The boy didn’t make any noise but the people from the viewing platform were screaming.”

Metropolitan Police said they arrested a 17-year-old boy on suspicion of attempted murder. The victim did not know the teen, cops said.

The suspect “had remained with members of the public on the 10th floor viewing platform,” police said.

The gallery — the most visited tourist attraction in the UK in 2018 — was put on lock down as officers dealt with the incident. Visitors were later allowed to leave, but the museum remained closed for the rest of Sunday.

With Post wires