Nodar Kumaritashvili, 21, was training at the Whistler Sliding Centre in Whistler, B.C., when his sled veered off the Olympic track and crashed into a steel pole at 90 mph.
His death "clearly casts a shadow over these games," said International Olympic Committee President Jacques Rogge, who was overcome with emotion at a press conference. "This is indeed a sad day. I have no words to say."
An investigation has begun into the circumstances of the crash.
"We are deeply struck by this tragedy," says John Furlong, chief executive of the Vancouver organizing committee, "and join the IOC in extending our condolences to the family, friends and teammates of this athlete, who came to Vancouver to follow his Olympic dream."
According to an official statement, Kumaritashvili crashed during the final run of training for the men's singles.
"He fell out of the track when he crashed," the statement says. "He was treated on site by medical staff who administered CPR, and was then taken away in an ambulance."
After the accident, training was immediately suspended. Before Friday's crash, athletes had raised concerns about the safety of the Whistler track. Already several athletes, including Romania's Violeta Stramaturaru, who was knocked unconscious, have been involved in crashes on the course, which is used for luge, skeleton and bobsleigh.
Kumaritashvili has competed in five World Cup races this season already, and was ranked 44th in the world standings.