Motorsport: Formula One stars Lewis Hamilton and Jenson Button led the tributes to Dan Wheldon after their fellow Englishman died in Sunday's Las Vegas Indy 300 race.
The 33-year-old two-time Indianapolis 500 winner was taken to hospital in a helicopter after his car was involved in a massive 15-vehicle crash, his vehicle flying over another on lap 11 of the race.
IndyCar chief executive Randy Bernard later confirmed that Wheldon 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 Scotsman 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 recently been working on a testing programme for enhanced safety measures.
Hamilton, the 2008 Formula One 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 extremely talented driver. As a British guy, who not only went over to the States but who twice won the Indy 500, 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."
Hamilton's McLaren team-mate and fellow former world champion Jenson Button paid tribute to Wheldon on Twitter.
He wrote: "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. I can't begin to imagine what his family are going through and my thoughts are with them at this very difficult time."
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.
Two-time Indianapolis 500 winner Wheldon had been in line to win €3.6 million ($5 million) had he won the race, which he entered via invitation. He was representing Sam Schmidt Motorsports having lost his place at Panther Racing.
Franchitti - who was confirmed as the IndyCar 2011 champion after the race was called off - insists warning signs were there.
"I could see within five laps people were starting to do crazy stuff," Wheldon's former Andretti team-mate, who was not involved in the crash, told IndyCar.com. "I love hard racing but that to me is not really what it's about. One small mistake from somebody..."
He added: "Right now I'm numb and speechless.
"One minute you're joking around in driver intros and the next he's gone. He was six years old when I first met him. He was this little kid and the next thing you know he was my team-mate.
"We put so much pressure on ourselves to win races and championships and today it doesn't matter."
Buckinghamshire-born Wheldon, a father of two who lived with his wife and sons in Florida, won 16 times in his IndyCar career and was the series champion in 2005.
Wheldon started at the back of the 34-car line-up but quickly started to make his way through the field before the pile-up, which injured three other drivers.
His colleagues were reportedly told of his death around two hours after he was airlifted from the Las Vegas Motor Speedway track to University Medical Center.
Wheldon becomes the first IndyCar fatality since American rookie Paul Dana was killed in a practice session five years ago.