Dale Oen, who won the gold medal in the 100m breaststroke in the 2011 World Championships in Shanghai, was found dead on Monday in a shower at a swimming pool in Flagstaff, Arizona, where Norway's national swim team was training for the London Olympics.
Photo: Krister Sørbø/NTB scanpix
The cause of death was not immediately known.
The swim federation said his teammates thought he was taking an unusually long time in the shower, and there was no reply when they knocked on the door. When they entered, Dale Oen was found lying on the floor.
The team doctor tried to resuscitate him, as did ambulance paramedics who arrived within minutes to take him to hospital.
"After more than an hour's attempts to get his heart going, Alexander Dale Oen was declared dead at 9:00 pm local time," the federation said.
"We're all in shock, this is like an out-of-body experience for the whole team here," Norway team coach Petter Loevberg said.
According to Norwegian daily Aftenposten online, Dale Oen had spoken to his family on Skype earlier in the evening "and there was no indication then that he was sick."
Dale Oen became Norway's first swimmer to win an Olympic medal when he won the silver in the 100m breaststroke in the 2008 Games in Beijing.
He had been tipped as one of Norway's best chances at a medal at the London Olympics in July.