NASCAR legend Kyle Busch's family reveals his cause of death
Busch, 41, died on Thursday after being hospitalized with a "severe illness."
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."
"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."
Sepsis is a life-threatening emergency and can affect anyone.
The longer it’s left untreated, the higher the mortality rate, which can increase hourly.
"It just overwhelms the body's immune system and then that bacteria spreads to the blood, which causes this reaction," ABC News Contributor Dr. Alok Patel said.
Sepsis can be due to any sort of infection like pneumonia.
"Anyone can have pneumonia and while younger adults are less likely to die from it, once they develop sepsis, they can rapidly deteriorate and become very sick, very quickly," said ABC News Medical Unit Fellow Dr. Jennifer Miao.
"Even though the people who are most vulnerable for sepsis, for getting complications, are young children, the elderly, or people with underlying medical conditions, it really can affect anyone," Patel said.
At least 1.7 million adults and more than 18,000 children develop sepsis annually, according to data from the U.S. Centers for Disease Control and Prevention.
At least 350,000 adults and more than 1,800 children die from it each year, according to the CDC.
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' Dr. Jennifer Miao, Meredith Deliso, Stefan Joyce and Victoria Arancio contributed to this report.