NASCAR star Kyle Busch experienced shortness of breath, felt he was overheating and was coughing up blood the day before his death, according to a 911 call obtained Friday by CBS News.

Busch died Thursday at age 41. No cause of death has been given, though his family said earlier he had been hospitalized with a "severe illness" three days before he was to compete in the Coca-Cola 600 at Charlotte Motor Speedway in North Carolina.

Busch was testing in the Chevrolet racing simulator in Concord, North Carolina, 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.

During the emergency call placed late that afternoon from the General Motors training facility, an unidentified caller calmly told the dispatch: "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."

Busch was lying on the bathroom floor inside the complex and the caller told dispatch "He is awake," according to audio provided by the Cabarrus County Sheriff's Office.

The man then gave directions on where emergency responders should go and asked that they turn off any sirens upon arrival.

NASCAR legend Jimmie Johnson, a former teammate of Busch, expressed shock and sadness at the sudden loss.

"I'm kinda lost for words at this moment, but we're gonna miss you, buddy. Gone too soon to say the least," Johnson told "CBS Mornings" on Friday.

He described Busch as "just that spirited, ruthless competitor on track. And I use ruthless in the best way possible. If you took an inch, he was going to take two. And there was an amount of respect on the track that you just showed him, as a result. At the same time, [he] would race you so hard and so clean, and just an incredible competitor."

According to Richard Childress Racing, Busch had 63 wins in the NASCAR Cup Series and held an all-time NASCAR record with 19 consecutive seasons with a victory from 2004 to 2023.

"Throughout a career that spanned more than two decades, Kyle set records in national series wins, won championships at NASCAR's highest level and fostered the next generation of drivers as an owner in the Truck Series," the statement said. "His sharp wit and competitive spirit sparked a deep emotional connection with race fans of every age, creating the proud and loyal 'Rowdy Nation.'"

His death came 11 days after Busch radioed into his crew near the end of a Cup Series race at Watkins Glen asking a doctor to give him a "shot" after he finished the race. According to the TV broadcast, Busch had been struggling with a sinus cold that was exacerbated by the intense G-forces and elevation changes at the New York road course.

Busch finished the race in eighth place.