Just to make this clear to everybody: there are no signs at all that this fire was arson. There are multiple explanations for the cause of the fire involving the construction site and some sort of negligence, which seem highly likely to be true.
The original website that had a map of these events (that you had to look up yourself to see they amounted to nothing) isn't even online anymore as far as I can see, now this false fact is just a urban legend with a life of its own.