jannik andersen , 23 , was attending coachella music festival at weekend .
he was struck and killed by a freight train at 3 am saturday , officials said .
crash occurred in pacific street in indio , four miles north-east of festival .
coroner says it is too early to tell whether drugs or alcohol played a role .
andersen , a student in boulder , described by friends as a ` genuine dude '
singer at festival , mac demarco , said on twitter : ` rip jannik andersen '