Racing enthusiasts have not yet come out of the shock of the tragic death of British IndyCar star Dan Wheldon in a 15-car pile-up at the season-ending Las Vegas 300 last week, when yet another fatal incident rocked the racing world on Sunday.

Italian motorcyclist Marco Simoncelli, 24, one of the top motocross riders in the world, was killed in a terrible collision at the Malaysian MotoGP motorcycle race in Kuala Lumpur. At turn 11, Simoncelli fell from his bike and slid into the path of Colin Edwards and Valentino Rossi, losing his helmet in the ensuing crash, The Telegraph reported.

Authorities immediately red flagged the race. Simoncelli was motionless on the track. He was then taken to the circuit's medical centre by ambulance. But after 45 minutes, he was pronounced dead due to a very serious trauma to the head, to the neck and the chest.

It was quite difficult to tell how the crash occurred. After just four minutes into the race, Simoncelli had lost control of his Honda at Turn 11. His bike skidded across the track and got hit by competitors Edwards and Rossi. Edwards dislocated a shoulder in the crash, but Rossi returned to the pits.

According to BBC MotoGP presenter Matt Roberts, when the track medics got to Simoncelli, he was in cardiac arrest. They tried to resuscitate him in the ambulance and the medical centre, The Telegraph quoted Roberts as saying. Both riders collided with him and the impact corresponded to him losing his helmet. The saddest thing is that Valentino and Marco were very close friends.

Everybody involved in MotoGP extends its deepest condolences to Marco's family, friends and team at this tragic loss, reads a statement on the official MotoGP Web site.

Tributes for the talented rider flooded Twitter on Sunday.

'R.I.P Marco... Such an exciting talent lost. My thoughts are with his family, friends and everyone involved in MotoGP. Motorsport can be so cruel... British Formula One driver Jenson Button wrote on his account.

'My thoughts are with his family, friends and team at this extremely sad time. Another tragic loss at such an early age, Button's Formula One teammate Lewis Hamilton wrote.

MotoGP champion Casey Stoner wrote: 'I'm so shocked and saddened by the loss of Marco. When things like this happen it reminds you how precious life is.

I watched the images and I'm shocked: in a race you fight and push hard and disaster is often around the corner, The Daily Mail quoted Simoncelli's compatriot and Repsol Honda rider Andrea Dovizioso. Marco was a strong rider and he always pushed hard. We raced together since we were kids, I saw him always pushing to the maximum, he crashed many times, but without major injuries, he was seemed invincible. What happened today seems impossible.

In 2008, Simoncelli won the 250cc world championship in Sepang. He stepped up to MotoGP in 2010. Simoncelli's death takes the number of recorded deaths in MotoGP to 47 since it was founded in 1949.

MotoGP race director Paul Butler promised a thorough investigation in to the matter.

We had our standard operating procedure ... this is one-of-a-kind freak incident where the helmet came off and I am sure [motorcycling body] FIM and MotoGP will be looking into this, he said.

You can never guarantee a 100 per cent safe race. You expose yourself 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.

Here are the videos:

Twitter Twitter