Fire was most likely started by vagrants burning stuff to keep warm in the partially completed building. This is going to be a case study for us in the insurance industry like Andrew was in FL. Will likely change building codes as they were using Podium Construction (5 floors of modified fire resistive frame on top of 3 stories concrete parking garage) which is a fairly new construction type. Fire breaks were not in yet so it burned much faster than it would once complete.
Same thing happened in Worcester Mass, about 15 years ago or so in empty industrial era warehouses/factories...vagrants started huge fires...several firefighters lost their lives.
Thankfully no one was killed in this one. Property damage and loss of income for everyone involved will be in the 100's of millions though. The building that burned down was $29M completed on a $50M job. Not to mention damage to the 17 story Qarum Center full of hundreds of luxury condos and The Link (204 apartments) both of which will be uninhabitable for months as well as 8 other buildings that suffered damage.
If I remember correctly, the Worcester vagrants/homeless responsible for the fire were sentenced to lengthy prison terms for manslaughter and arson. Now they ended getting 3 squares and a comfy bed. Ironic, isn't it?? Our "justice" system, interns of inflexible logic, really needs revamping....