Kyle Busch died after severe pneumonia progressed into sepsis, family says

Busch, who was preparing to race Sunday at the Coca-Cola 600 at Charlotte Motor Speedway, was testing in a Chevrolet racing simulator Wednesday when he became unresponsive - (Getty Images)

NASCAR champion Kyle Busch died after severe pneumonia progressed into sepsis, resulting in rapid and overwhelming complications, according to a statement from his family.

Busch died on Thursday, a day after he became unresponsive in a racing simulator. The two-time champion was 41 years old.