CONCORD, N.C. (AP) — Kyle Busch, a two-time Cup Series champion who won more races than anyone across NASCAR’s three national series, has died. He was 41.

The Busch Family, Richard Childress Racing and NASCAR issued a joint statement Thursday saying Busch died after being hospitalized.

No cause of death was given.

Busch’s family said earlier Thursday that he was hospitalized with a “severe illness,” three days before he was to compete in the Coca-Cola 600 at Charlotte Motor Speedway.

Busch was testing in the Chevrolet racing simulator in Concord on Wednesday when he became unresponsive and was transported to a hospital in Charlotte, several people familiar with the situation told The Associated Press on condition of anonymity because details have not been disclosed by Busch’s team or family.

Busch was the younger brother of Kurt Busch, a NASCAR Hall of Famer.

He’s survived by wife Samantha and children Brexton and Lennix.

“Our entire NASCAR family is heartbroken by the loss of Kyle Busch,” the statement said.