London (CNN) A 6-year-old boy wandered just a few feet from his mother when a 17-year-old stranger allegedly picked him up and "swiftly" threw him off the 10th floor viewing platform at London's Tate Modern art gallery, a court has heard.

The teenage suspect has been charged with attempted murder and briefly appeared at Bromley Youth Court in London on Tuesday. His name can't be reported because of his age.

The French boy, who was visiting the gallery with his family on Sunday, fell around 100 feet to the fifth floor roof, prosecutor Sian Morgan told the court.

According to Morgan, the boy is in hospital with a bleed to his brain and fractures to his spine, legs and arms. He was airlifted to the hospital by a helicopter on Sunday. The court was told his life was likely saved because of the way the roof floor slants, said the prosecutor.

"(The) victim had gone to the Tate with his family that day and were looking over the side of the 10th floor viewing platform enjoying the view," Morgan told the court. The boy then "walked a few feet away from his mother" when the defendant allegedly "picked him up and threw him extremely swiftly and in one movement."

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