The racing world is mourning the loss of NASCAR star Kyle Busch, who died at 41 after suddenly falling seriously ill.

NASCAR star Kyle Busch was found unconscious in a driving simulator just one day before his death on May 21, according to reports cited by the New York Post.

He was taken to a hospital in Charlotte, North Carolina, after suffering what his family initially described as a severe illness. Just hours before his passing, Busch’s family had announced he would miss two upcoming races.

It has since been found that the two-time Cup Series champion had developed pneumonia, which later led to sepsis.

Because sepsis can resemble many common illnesses in its early stages, it is sometimes referred to as a ‘silent killer.’ The condition develops when the body’s response to an infection begins damaging its own organs and tissues instead of protecting them which can make their health deteriorate quickly.

The Mayo Clinic explains that symptoms vary, which is another reason sepsis can be so difficult to identify. Some people may begin shivering or sweating heavily, feel dizzy or lightheaded, or notice unusually fast and shallow breathing. Confusion, disorientation and changes in mental state can also be warning signs.

Busch’s death has shocked NASCAR
In a joint statement issued by NASCAR, Richard Childress Racing and Busch’s family, the father-of-two was remembered as a remarkable talent whose loss has shaken the sport.

“A future Hall of Famer, Kyle was a rare talent, one who comes along once in a generation. He was fierce, he was passionate, he was immensely skilled and he cared deeply about the sport and fans. NASCAR lost a giant for the sport today, far too soon.”