NASCAR champion Kyle Busch died Thursday at age 41 following a medical emergency at a General Motors training facility in Concord, North Carolina. According to a 911 call obtained by The Associated Press, Busch experienced severe breathing difficulties, overheating, and was coughing up blood the day before his death while testing in a Chevrolet racing simulator.

The emergency call revealed Busch was unresponsive and lying on a bathroom floor when first responders arrived. He had been hospitalized three days earlier with what his family described as a severe illness, just before he was scheduled to compete in the Coca-Cola 600 at Charlotte Motor Speedway. Authorities have not released an official cause of death.

Busch was a two-time NASCAR Cup Series champion and one of the sport's most successful drivers, with 233 career victories across NASCAR national series. His death shocked the racing community and leaves a significant void in the sport. The investigation into the circumstances surrounding his medical emergency continues as the NASCAR world mourns the loss of one of its biggest stars.