Two motorcycle racers killed in California track crash (VIDEO)

Two Spanish motorcycle racers were killed in a horrific chain-reaction crash on the first lap of a World Superbike race, leaving the cycle-racing world overwhelmed with sadness and raising questions about what happened on the track.

The deaths occurred Sunday at Mazda Raceway Laguna Seca in California during the MotoAmerica Superbike/Superstock 1000 race, Monterey County sheriff’s spokesman Cmdr. John Thornburg said.

The track was dry during the race and it appears to just be an unfortunate accident, said MotoAmerica spokesman Paul Carruthers said.

Carruthers said there were 28 riders in the race and thousands of spectators in the stands when five competitors collided on the first lap and the riders and their bikes went flying into the dirt on the side of the track.

Carruthers declined to comment on whether MotoAmerica, which organizes the race, will investigate.

MotoAmerica identified the riders killed as 35-year-old Bernat Martinez of Alberic, Valencia, Spain; and Daniel Rivas Fernandez, 27, of Moana Galicia, Spain. Both were taken to hospitals, where they died.

MotoAmerica and Mazda Raceway Laguna Seca's statement on today's tragedy. http://t.co/2ytPgNwDtm pic.twitter.com/EkC6Xk4YNO

— MotoAmerica (@MotoAmerica1) July 20, 2015

Four other riders were treated at the track and released. Their names were not released.

It was not immediately clear what led to the crash, track spokesman David Hart said, adding that Laguna Seca will conduct an investigation.