Shoya Tomizawa has died as a result of injuries sustained in the Moto2 race on Sunday at Misano.
The Japanese - who made history by winning the first ever Moto2 Grand Prix at Qatar this year, then took pole and a podium at round two - fell from fourth place on lap 12 and was then hit at high speed by Alex de Angelis and Scott Redding.
The official statement from Dorna announcing the death was as follows:
"On Sunday 5th September during the Moto2 race at the Misano World Circuit, rider Shoya Tomizawa aged 19 suffered a serious crash and subsequent cranial, thoracic and abdominal trauma.
"Given the seriousness of his condition - especially for the thoracic and abdominal trauma - Tomizawa was immediately treated at the Misano World Circuit medical centre and put under artificial respiration.
"The rider was taken by ambulance to the Riccione hospital accompanied by two doctors - helicopter was not used in order to allow for the proper respiratory support to be administered. Despite various attempts to resuscitate him Shoya sadly succumbed to his injuries at 14.20.
"Everybody involved in MotoGP extends its deepest condolences to Shoya's family and friends at this tragic loss."
de Angelis walked away from the huge accident, while Redding received ten stitches for a back laceration. Neither rider had any chance to avoid Tomizawa, who was sixth in the world championship heading into the race.
2010 was Tomizawa's second season in grand prix racing, after finishing 17th in the 2009 250cc class.
Prior to last year, Tomizawa had been a wild-card rider at his home Motegi event in 2006 (125cc), 2007 (125cc) and 2008 (250cc).
Tomizawa was runner-up in the 125cc Japanese Championship in 2006 and the 250cc Japanese Championship in 2008.
The last time a rider was killed during a motorcycle grand prix was Daijiro Kato, in the MotoGP class, at Suzuka 2003.
Our thoughts are with Tomizawa's family and friends.