Kyle Busch, a two-time NASCAR champion, has died aged 41 after being taken to hospital with a "severe illness".
In a joint statement, the Busch family, NASCAR and Richard Childress Racing - the team Busch competed for - said they were "heartbroken" at the loss of "a giant of the sport".
They paid tribute to "a rare talent, one who comes along once in a generation" and someone who "sparked a deep emotional connection with race fans of every age".
Busch's representatives said on Thursday that he had been taken to hospital with a "severe illness", with the announcement of his death coming hours later.
No cause of death has been given.
The joint statement described Busch as an "immensely skilled" racer who "cared deeply about the sport and fans".
In its own statement on social media, NASCAR hailed Busch as "one of our sport's greatest and fiercest drivers".
Busch, the younger brother of NASCAR Hall of Famer Kurt Busch, was in his 22nd full-time season in NASCAR's top division, where he had won two Cup Series titles and more than 60 races.
He had been due to compete in the Coca-Cola 600 at Charlotte Motor Speedway in the US on Sunday. The event, NASCAR officials told The Associated Press, will go ahead as planned.
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It is not the first tragedy the NASCAR community has had to contend with in recent months.
In December, former driver Greg Biffle, his wife and two children were among those killed in a plane crash at an airport in North Carolina.
The other three people who died in the incident - Craig Wadsworth, and Dennis and Jack Dutton - were all "beloved by many in the NASCAR community", according to the racing organisation.
Biffle, 55, won more than 50 races across NASCAR's three circuits, including 19 at the top-level Cup Series.
(c) Sky News 2026: Two-time NASCAR champion Kyle Busch dies aged 41 - after being taken to hospital with 'seve
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