Eye witnesses as well as pictures confirmed that a cable snapped in two.
Upstop, the rides brakes are magnetic and can only fail in the event of the Earth's magnetic poles switching. There are cables that bring the car up to the top of the tower, an most likely, the cable that snapped was on the same vehicle. Those cables are under intense tension and if it snapped, it is highly probable that the cable shot down underneath the car and unfortunately came in contact with the young girl. With regards to DZ at KI, if any of the cables did snap, the seats are far enough away to more than likely not come into contact with it. I don't remember if someone asked on this site if DZ's ride vehicle is further away because of this potential risk but that isn't the reason. It is like that to be able to hold more passengers. This is a true freak accident that was way beyond "worst case scenario". Even preparing for a cable snap during design cannot predict the violent behavior of something under such high tension. This is very tragic and the girl and her family, as well as the many witnesses including the ride operators, need our prayers.