The multi-bike accident happened on the first lap of Sunday’s second MotoAmerica race, with Spaniards Bernat Martinez, 35, and Daniel Rivas Fernandez, 27, both badly injured.

The pair were transported straight to hospital. Martinez was taken to Community Hospital of the Monterey Peninsula, while Fernandez was sent to Natividad Medical Center. Both later succumbed to their injuries.

In a statement issued on Sunday night, MotoAmerica president Wayne Rainey said: "I really don't have any words to describe what we all feel.

"First and foremost, is the loss to the families and loved ones. Our sincere condolences goes out to each and every one of them as well as the MotoAmerica family. They are in our thoughts and prayers."

"We are deeply saddened to learn the news of the passing of Bernat Martinez and Daniel Rivas," added Gill Campbell, CEO and general manager of Mazda Raceway Laguna Seca.

"Our prayers and hearts go out to their families and teams."