French gymnast Samir Ait Said suffered a horrific leg break while performing in the vault at the Rio Olympics.
The 26-year-old's left leg folded beneath him as he landed badly during the men's qualification event.
Said, who won gold on the rings at the 2013 European Championships, was taken off on a stretcher and acknowledged the crowd as he departed.
I heard other gymnasts say 'don't look, don't look'
United States gymnast
French team leader Corrine Moustard-Callon said: "We don't know what happened, except it was his tibia."
She added: "He is in the hospital with a doctor now. We will do more exams to see if it is just the bone.
"It is very difficult for the team. He was one of the friendliest on the team which is very difficult — he came to win a medal and gave everything, 200%."
United States gymnast Danell Leyva, the 2012 Olympic all-around bronze medallist, added: "I heard other gymnasts say 'don't look, don't look'.
"Even though we're on different teams we know each other and I've known Samir since I was 14. It really sucks, but we have a job to do."
Highlights footage and photos of the injury are too graphic to be shown on the BBC Sport website.