NASCAR legend Kyle Busch, who passed away suddenly and unexpectedly earlier this week, died of severe pneumonia that turned into sepsis, according to the driver’s family.

“The medical evaluation provided to the Busch Family concluded that severe pneumonia progressed into sepsis, resulting in rapid and overwhelming associated complications,” the Busch family statement read. “The Family asks for continued understanding and privacy during this difficult time.”

The family received the medical evaluation on Saturday, according to Dakota Hunter, VP of Kyle Busch Companies.

Busch died Thursday after being rushed to the hospital.

911 audio obtained by TMZ Sports reveals that Busch, 41, was coughing up blood the day before he succumbed to what is being described as a “severe illness.”

The call, placed at 5:30 PM local North Carolina time, provides a detailed account of the seriousness of the medical event affecting Busch, with the caller describing the driver’s breathing as labored and saying the 41-year-old was coughing up blood and overheating.

“I’ve got an individual that’s shortness of breath, very hot, thinks he’s going to pass out, and he’s producing a little bit of blood, coughing up some blood,” the caller explained.

The caller added, “He is awake. He’s awake. He’s awake.”

Repeated pleas were made for ambulances to respond to the testing facility at Richard Childress Racing, where Busch was lying on the bathroom floor.

Busch was found unresponsive while testing a Chevy racing simulator only a day before.

The legendary NASCAR racer revealed in a television interview on May 10 that he had been battling a sinus condition,

Despite that, he continued to race, notching a win in a Truck Series race on May 15 and participating in a NASCAR All-Star race on May 17, which turned out to be his final competition.

He is survived by his wife, Samantha, his 11-year-old son, Brexton, and his 4-year-old daughter, Lennix.