It seems that Kurt Caselli had a crash on an animal which resulted to the accident that claimed his life. 

According to the Ktm press release concerning the accident, there were traces on the bike indicating impact with an animal, which caused the crash, resulting to head injuries. The accident occurred in Ensenada, Baja California, Mexico. 30 y.o. American rider Kurt Caselli lost his life during the Baja 1000 race. It is believed that the Ktm rider crashed to a booby-trap which is a common technique by spectators who dig jumps and obstacles in order to better the racing spectacle.