Watched a separate video of eyewitness accounts from those standing in the queue. One speculated that the operator feared someone was slipping out the ride and hit the emergency stop button in a panic. The result brought the ride to an abrupt halt and looked to be the cause of at least two riders being ejected, as well as one of the seating rows to be sheared off and thrown from the structure. Obviously speculative, but the video and account are terrifying and tragic put it lightly. While these types of accidents are such a statistical anomaly, they are truly horrific.
Thoughts and prayers to all those affected.