It is very sad
My thoughts are with every one close to her.
Since it is the first time, I have ever heard of an accident like that, my thoughts are that she must have had a small defect in the brain, that had burst on impact. I have heard about prof. soccer players suddently die on the field, from heart attacks, teakwon do fighters die from a small kick to their neck, causing a damage in their brain. All these sad accidents came from small defects, they weren't aware off.
All this doesn't make a difference to what had happened. Sad! Very Sad!