Norway's world 100 metre breaststroke champion Alexander Dale Oen has died.
Dale Oen, who was 26, was in Flagstaff, Arizona at a training camp where he is reported to have had a cardiac arrest.
Starla Collins, a spokesperson for the Flagstaff Medical Center, confirmed Dale Oen had died but could not provide any more details.
Dale Oen won the 100m breaststroke at the World Championships in Shanghai last July, three years after claiming Olympic silver in Beijing.
He was one of Norway's top hopes for success at this summer's Olympic Games in London.
Per Rune Eknes, the president of the Norwegian Swimming Federation, told www.vg.no: "This is just awful, especially for the family and close friends, and also the sport of swimming."
Norwegian media report Dale Oen was found on the bathroom floor at 9pm local time on Monday.
He was taken by ambulance to the medical center where, despite repeated attempts at resuscitation, he was pronounced dead.
The Norwegian team coach Petter Lovberg told www.vg.no: "We are all in shock, this is an out-of-body experience for the whole team over here.
"Our thoughts go out to his family who have lost Alexander too early.
"Words cannot describe the grief they must feel.
"For us here in Flagstaff it is important now that we stand together and take care of each other.
"It is an unreal situation and we have some tough days ahead."