When reading ALL the reports available - however sketchy. It would appear that Kevin Ash, lost control of his bike, on a dirt, rutted and very dusty gravel road. He was apparently following many other, very experienced Off-Road Bikers. He lost it and came off. He fell to the ground.
But as in Marco Simoncelli's case, he was hit by a following rider, which resulted in his fatal injuries.
A Tragic Accident.
Seems that the rider that collided with him, who was also injured- (dislocated shoulder) is now being investigated for :- Culpable Homicide.
Time will tell.