The Kyle Busch family released a statement May 23 revealing what killed the two-time NASCAR Cup Series champion, two days after his sudden death.

Kyle Busch's family earlier Thursday announced he had been hospitalized with a "severe illness."

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.

Busch, a two-time NASCAR champion, died at 41 on Thursday

Kyle Busch died after severe pneumonia progressed into sepsis, leading to rapid complications.