NASCAR legend Kyle Busch's family reveals his cause of death

NASCAR legend Kyle Busch died from complications from "pneumonia [that] progressed into sepsis," his family revealed Saturday.

Busch died on Thursday at the age of 41, just hours after his family said he had been hospitalized due to a "severe illness" and that he would not be competing this weekend at Charlotte Motor Speedway.

The family said in a statement they were provided with the new details from a "medical evaluation," and that the illness resulted  "in rapid and overwhelming associated complications."NASCAR great Kyle Busch was coughing up blood day before he died, 911 call says

"The Family asks for continued understanding and privacy during this difficult time," the statement said.

A day before he died, Busch had been at the GM facility in Concord, North Carolina, when he started coughing up blood, according to a 911 call obtained by ABC News.

The 911 caller requested an ambulance come for an individual experiencing "shortness of breath" who was "very hot, thinks he's going to pass out."NASCAR community and beyond pays tribute to race car legend Kyle Busch

Busch won the NASCAR Cup Series twice -- in 2015 and 2019 -- and set records in national series wins. His two-decade career included 234 victories among all three NASCAR national series.

He is survived by his wife, Samantha, and their two children, Brexton, 11, and Lennix Key, 4.

It was announced on Friday that Kyle Busch's No. 8 car will be retired and reserved for his son "when he is ready to go NASCAR racing."

-ABC News' Meredith Deliso, Stefan Joyce and Victoria Arancio contributed to this report.