Moto2 rider Luis Salom died after crashing during practice for the Catalunya Grand Prix on Friday. He was 24.
The death of the Spanish rider was announced at a news conference a few hours after the incident in Barcelona.
"He underwent surgery but despite the best efforts of the trauma team, he passed away," said Giancarlo Di Filippo, a medical director for the International Motorcycling Federation.
The crash happened at Turn 12, a fast right-hander near the end of the track. The turn is not used in Formula One, where cars have to go through a chicane to slow down before entering the front straight.
The official race broadcast did not appear to catch images of the accident, but a security camera at the track showed Salom was not able to make the turn. His bike slid straight across the track and the rider followed behind, crashing into the safety barrier. It wasn't clear if Salom also collided with his bike before hitting the barrier.
"We have to see if something broke on his bike," veteran MotoGP rider Valentino Rossi said. "It appeared he went straight."
Salom stayed on the ground virtually motionless as track stewards rushed to him. Two medical cars and two ambulances quickly arrived and doctors spent several minutes treating him.
A helicopter also landed on the track, but "due to the severity of his condition" he was taken to the hospital in an ambulance so doctors could continue working on him.
It was not immediately clear what type of surgery doctors performed on him.
The session was red-flagged with about 25 minutes left before being eventually canceled.
Salom had been in Moto2 since 2014 and had three podium finishes in 41 races, including a second place in this season's opener in Qatar. He was 10th in the point standings.
He had nine wins in Moto3 and finished second in the championship in 2012 and third in 2013.