Kyle Busch's Cause Of Death: What We Know So Far

Busch's family confirmed his passing, as well.

"Our entire NASCAR family is heartbroken by the loss of Kyle Busch. A future Hall of Famer, Kyle was a rare talent, one who comes along once in a generation. He was fierce, he was passionate, he was immensely skilled and he cared deeply about the sport and fans. 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. His sharp wit and competitive spirit sparked a deep emotional connection with race fans of every age, creating the proud and loyal 'Rowdy Nation.' Our thoughts are with Samantha, Brexton and Lennix, Kyle and Samantha's parents, Kurt and all of Kyle's family, Richard and Judy Childress, everyone at Richard Childress Racing, his teammates, friends and fans. NASCAR lost a giant of the sport today, far too soon," his family wrote.

"During this incredibly difficult time, we ask everyone to respect the family's privacy and continue to keep them in your thoughts and prayers. Further updates will be shared as appropriate."

But what happened? Here's what we know so far.

What we know about Kyle Busch's death

Busch was hospitalized due to "severe" illness on Thursday morning. He was scheduled to miss this weekend's Coca-Cola 600. It was set to be the first time in a decade that Busch missed a race.

"Kyle Busch's health is our upmost priority and he and his family have the full resources of RCR behind them," RCR said in a statement earlier on Thursday. "Kyle is an integral part of our organization and we wish him a safe and speedy recovery. His No. 8 Chevrolet will be ready and waiting for him. We're thankful to Austin Hill for stepping in to drive the No. 8 Chevrolet this weekend. Please keep Kyle and the Busch family in your prayers, and help us respect the family's privacy at this time."

However, earlier this month, Busch needed medical assistance following a race. During the May 10 race at Watkins Glen, Busch was heard radioing for medical aid from Dr. Bill Heisel, asking for a "shot" after the race.

According to the broadcast, Busch had been "struggling with a sinus cold that was exacerbated by the intense G-forces and elevation changes at the Upstate New York road course."

It appears that Busch's health could have deteriorated quickly, though official details on his passing are unclear at this time.

Busch had previously said that you never know when your last race is going to be.

"You take whatever you can get, man," Busch said after his 69th career Truck series race win at Dover. "You never know when the last one is going to be, so cherish them all -- trust me."

Tributes for Busch are now pouring in online. Our thoughts are with his friends and family members during this difficult time.