LONDON (AP) — Police in London say a 6-year-old boy who was thrown from a 10th-floor viewing gallery at the Tate Modern gallery is no longer in a life-threatening condition.

A 17-year-old boy is being held on suspicion of attempted murder over the incident, which came Sunday as the gallery was packed with visitors.

The Metropolitan Police says the younger boy is in a critical but stable condition in a London hospital. He fell from the open-air viewing platform to a fifth-floor roof.

Nancy Barnfield was at the gallery when she heard a "loud bang," and then saw a woman screaming "where's my son, where's my son?"

Police say they don't believe the suspect and victim knew each other.

Tate Modern was visited by almost 6 million people last year.