Celebrated Italian rider Marco Simoncelli died on Sunday after a crash that resulted in the cancellation of the Malaysian MotoGP at Sepang, in the latest tragedy to hit motor sports.
The smash occurred just minutes after the race began when the 24-year-old Honda rider's bike veered across the track and into the path of riders Colin Edwards and Valentino Rossi.
Simoncelli had his helmet knocked off in the collision, which happened on turn 11.
"Despite their efforts, Marco sadly succumbed to his injuries at 4:56pm local time (0856 GMT)," MotoGP said in a statement on its website.
"Everybody involved in MotoGP extends its deepest condolences to Marco's family, friends and team at this tragic loss."
Motor sports have seen a nightmare stretch recently and Simoncelli's death looked certain to throw up more questions over safety.
Last weekend, 2010 MotoGP champ Jorge Lorenzo crashed during warm-ups in Australia, severing a finger, while two-time Indianapolis 500 winner Dan Wheldon died in a 15-car crash in Las Vegas in Indy Car.
The race at a steamy Sepang circuit was immediately red-flagged and organisers later announced it had been cancelled.
Edwards also fell but escaped serious injury, while Rossi was able to return to the pits.
After the crash, restless fans upset with the lengthy delay following it showered the track with water bottles and other debris.
The last fatal crash in the world motorcycling championship was last year when Japan's Shoya Tomizawa was killed.
Although there is a final race in Spain still to come, Australia's Casey Stoner has already secured the 2011 championship with his win last weekend in the Australian Grand Prix.
Stoner won at Phillip Island by just two seconds over Simoncelli, whose second-place finish was the Italian's best yet in MotoGP. He was the 2008 world champion in the 125cc class.
"You can never guarantee a 100 percent safe race," Sepang Circuit chairman Mokhzani Mahathir told reporters after Simoncelli's death was announced.
"You expose youself to danger when you race. As professionals, they know MotoGP is dangerous. Believe it or not, that is what they live for. Our condolences to Marco. He will be missed dearly."
Simoncelli's death quickly sparked an outpouring of grief in Italy, where officials announced sports events in the country would observe a minute's silence.
Italian football giants Inter and AC Milan were amongst the first sports clubs to offer their commiserations.
"AC Milan offers a hug to the family of Marco, a huge rossonero fan, and we want to offer the most sincere and heartfelt condolences in this sad moment," the club said on its website.
Inter added: "The president Massimo Moratti and everyone at Inter Milan, together with (coach) Claudio Ranieri and the team, shares in the pain of the Italian sports world and indeed the sports world for the loss of the rider Marco Simoncelli.
"Remembering a young and passionate champion Inter offers a hug to the family and friends of Marco Simoncelli."