FORMULA One drivers Lewis Hamilton and Jenson Button led the tributes to Dan Wheldon after their fellow Englishman was killed in yesterday's Las Vegas Indy 300 race.
Wheldon, a two-time Indianapolis 500 winner, was taken to hospital in a helicopter after his car flew over another in a 15-vehicle crash on lap 11 of the race.
IndyCar CEO Randy Bernard later confirmed that Wheldon, 33, had died as a result of "unsurvivable injuries".
Wheldon's fellow drivers got in their cars to perform a five-lap salute in his honour after being told of his death.
One of them was fellow Briton Dario Franchitti, who claimed there had been warning signs of potential danger due to the number of cars in close confinement at such high speeds.
Figures from the world of motor racing were quick to pay tribute to the 2005 IndyCar series champion, who had been working on a testing programme for better safety measures.
Hamilton, the 2008 F1 world champion, said: "This is an extremely sad day. Dan was a racer I'd followed throughout my career, as I often followed in his footsteps as we climbed the motorsport ladder in the UK.
"He was an inspirational guy, and someone that every racing driver looked up to with respect and admiration. This is a tragic loss at such a young age. My heart goes out to his family and friends during this extremely difficult time."
Button, a fellow former world champion, paid tribute to Wheldon on Twitter: "Just woken up to the most horrific news ... Dan Wheldon RIP...
"I have so many good memories of racing with Dan in the early '90s, a true fighter. We've lost a legend in our sport but also a great guy."
The accident occurred when a number of cars came into contact on turn two, sending several of them flying through the air, smashing into the outside wall and catch fence.
With cars smouldering and debris littering the track, the race was red-flagged as crews worked on fences and removed the damaged cars.
Wheldon had been in line for $5m had he won the race, which he entered via invitation. He was representing Sam Schmidt Motorsports having lost his place at Panther Racing.
Franchitti was confirmed as this year's IndyCar champion after the race was called off.
Wheldon, a father of two who lived with his wife and sons in Florida, won 16 times in his IndyCar career.