Anyone remember “Towering Inferno”?
It would appear that the cladding used to modernize the exterior was highly flammable. Since several people survived the blaze, I would surmise that the interior of the building was not affected as much? With the fire progressing as quickly as it did, it would lead me to believe that the outer rim was the greatest hit.
The architect has stated that the materials he selected for the 2016 renovation were non-combustible. He also said he specified firebreaks around each window and between each floor. The contractor says he installed all the specified materials correctly.
I am sure there is an explanation somewhere.