Quote:
"Officials said the building has a fire suppression system, which was operating but was compromised when a portion of the roof collapsed. "
Seems like a design flaw in tilt wall construction? More common for that type of construction, walls will pull away from the roof, lessening support, roof collapses. Further just because the suppression system was "operational" does not mean it was at optimum output.
OTOH, how high were the paper products stacked? Did they go up to nearly the ceiling line? That would impede the functionality of a ceiling based water suppression system.
Whether or not this was arson, the mechanics of how this fire spread and why requires additional analysis.