The cause of death for NASCAR star Kyle Busch has not yet been publicly released following the two-time Cup Series champion's passing on Thursday at age 41.
Videos by FanBuzz
Busch's family announced his death in a joint statement with NASCAR and Richard Childress Racing, calling him "a rare talent" and "a future Hall of Famer."
While officials have not confirmed a specific cause, several details have emerged regarding Busch's health in the days leading up to his death.
According to reports, Busch became unresponsive Wednesday while testing in a Chevrolet racing simulator at the General Motors Charlotte Technical Center in Concord, North Carolina. He was transported to a Charlotte-area hospital.
Earlier Thursday, Busch's family announced he would miss the Coca-Cola 600 weekend because of what was described as a "severe illness resulting in hospitalization."
A 911 call obtained by NBC News indicated Busch was experiencing shortness of breath and coughing up blood before being hospitalized. A caller also said Busch felt extremely hot and believed he was going to pass out.
Busch had reportedly been battling what broadcasters described as a sinus cold earlier this month. During a race weekend at Watkins Glen on May 10, Busch radioed his team requesting medical attention after the event.
"You can kind of still hear it. I'm still not great," he said in an interview days later. "But the cough was pretty substantial last week."
It remains unclear whether those symptoms were related to his death.
Busch competed as recently as last weekend, winning a NASCAR Craftsman Truck Series race at Dover before finishing 17th in the NASCAR All-Star Race.
He leaves behind his wife, Samantha, and their two children.
