Kyle Busch died after severe pneumonia progressed into sepsis, resulting in rapid and overwhelming complications, according to a statement released by his family.

Dakota Hunter, vice president of Kyle Busch Companies, said in a news release the family received the medical evaluation on Saturday.

Busch, a two-time NASCAR champion, died at 41 on Thursday, a day after passing out in a Chevrolet simulator.

Sepsis is considered a life-threatening medical emergency that occurs when the body has an extreme, overactive response to an infection, causing the immune system to damage its own tissues and organs, according to the Centers for Disease Control and Prevention.

Busch was thought to have had a sinus cold while racing at Watkins Glen on May 10 and radioed in to his team saying that he needed a “shot” from a doctor after the race. However, he bounced back to win the Trucks Series race at Dover last weekend, and then he finished 17th in the All-Star race on Sunday.

Busch, who was preparing to race Sunday at the Coca-Cola 600 at Charlotte Motor Speedway, was testing in the Chevrolet racing simulator in Concord on Wednesday when he became unresponsive and was transported to a hospital in Charlotte, several people familiar with the situation told The Associated Press.

During the emergency call placed late that afternoon, an unidentified caller calmly told the dispatch: “I’ve got an individual that’s (got) shortness of breath, very hot, thinks he’s going to pass out, and is producing a little bit of blood, coughing up some blood.”

Austin Hill will replace Busch on Sunday and drive the No. 33 car. RCR is temporarily retiring Busch’s No. 8 until his 11-year-old son Brexton is old enough to race.

All 39 cars in the field for Sunday’s race will include a small black No. 8 decal to honor Busch.

Busch won 234 races across NASCAR’s top three series over his two-decade career, more than any driver in history.

Qualifying washout

Points leader Tyler Reddick will start on the pole for the Coca-Cola 600 at Charlotte Motor Speedway after persistent rain washed out NASCAR Cup qualifying on Saturday.

Rain remains in the forecast for Sunday’s crown jewel event.

Reddick’s No. 45 23XI Racing Toyota will start first when the green flag falls on the 400-lap race and will be joined on the front row by the No. 54 Toyota of Ty Gibbs from Joe Gibbs Racing. Trackhouse Racing’s Shane van Gisbergen, Spire Motorsports’ Michael McDowell and JGR’s Chase Briscoe round out the top five.

Katherine Legge, who is becoming the first woman to attempt “The Double” by running both the Indianapolis 500 and the Coca-Cola 600, will start 37th based on points.

Fireworks in F1 race

George Russell clashed early with Mercedes teammate Kimi Antonelli in the Formula One Canadian Grand Prix sprint race Saturday in Montreal, sending the teen star into the grass in an entertaining victory from the pole.

Russell fended off a pair of attacks from Antonelli on the sixth of 23 laps as the drivers made contact in Turn 1, forcing the 19-year-old into the grass.

“That was very naughty,” a furious Antonelli said over on the team radio.

Antonelli — the winner of the last three Grand Prix races — accused Russell of pushing him off before demanding a penalty.

Mercedes team principal Toto Wolff told Antonelli to “concentrate on the driving, please, not on the radio moaning.”

“Emotions were very high in the moment, and obviously I was very annoyed,” Antonelli said in an ensuing press conference, moments after a frosty finish-line handshake with Russell.