http://blackout.gmu.edu/archive/pdf/ny_state_77.pdf
see pages 3-12 of pdf doc (not footer page numbers). It details the exact sequence from first lightning stroke, failure of grounding, to collapse.
I do NOT, repeat NOT, say that this IS what happened here, just that
(a) it is quite plausibele, and
(b) it will take a full technical workup like this report to know for sure.