I looked at the same roof photo in another string here and it looks like this system might be hinged in the middle in the long 60' direction as the endwall of the atrium appears to be open - the one that has not collapsed. It appears to me that the one that has not failed has been raised slightly to allow for ventilation through the endwall opening. If this is the case, then I'm wondering if the short sides had rollers to allow the skylight to move to open. If one of the rollers locked for some reason, and the structure of the skylight could not handle the torsion, the roller could have jumped any track at the end, toppeling the structure into the opening below.
All conjecture. I'm sure we will get the story. Will be interesting to hear.
