Former NASCAR star Kyle Busch died of severe pneumonia at the age of 41, according to a statement released by his family on Saturday.

The statement said that the medical evaluation provided to them said the pneumonia progressed “into sepsis, resulting in rapid and overwhelming associated complications.”

Busch died Thursday, May 21 after being hospitalized with what his family called a serious illness.

His family revealed the update in an X post on May 21 at 10:23 a.m. ET and added that he would not be facing in this weekend’s competition.

“Kyle has experienced a severe illness resulting in hospitalization,” the family wrote. “He is currently undergoing treatment and will not compete in any of his scheduled activities this weekend at Charlotte Motor Speedway. We ask for understanding and privacy as our family navigates this situation.”

Details later emerged that Busch had become unresponsive the day before his death while testing a racing simulator in Concord, N.C., and had to be hospitalized, according to the Associated Press.

Busch’s family, NASCAR and Richard Childress Racing released a statement Thursday at 5:46 p.m. ET announcing his death.

“A future Hall of Famer, Kyle was a rare talent, one who comes along once in a generation,” the joint statement read. “He was fierce, he was passionate, he was immensely skilled, and he cared deeply about the sport and fans. Throughout a career that spanned more than two decades, Kyle set records in national series wins, won championships at NASCAR’s highest level and fostered the next generation of drivers as an owner in the Truck Series. His sharp wit and competitive spirit sparked a deep emotional connection with race fans of every age, creating the proud and loyal ‘Rowdy Nation.’”

Before his death, Busch had been battling a sinus issue.

The Las Vegas native said during a May 10 race at Watkins Glen in New York that he wanted to see a doctor, stating: “I’m gonna need a shot.”

The broadcast crew clarified that Busch had been struggling with a sinus issue, and they reportedly said, per the AP, that “Busch had been struggling with a sinus cold exacerbated by the intense G-forces and elevation changes at the New York road course.”

The sinus issue still affected Busch last week, leading into what would be his final competition at the NASCAR All-Star Race last Sunday, a 17th-place finish.

Busch told The Athletic while pointing at his face: “You can kind of hear it, I’m still not great. The cough was pretty substantial last week.”

The legendary racer will forever be known as one of NASCAR’s greatest drivers.

He won the Cup Series in 2015 and 2019 and ranks ninth all-time in NASCAR Cup Series wins with 63, while tallying the most wins across NASCAR’s three levels with 234.

Busch, nicknamed “Rowdy,” is survived by his wife, Samantha, 11-year-old son Brexton and 4-year-old daughter Lennix.