Looking at the structure still left to the south south of it the main body of the building is still standing and only the overhanging section collapsed.
I see 2 wing walls and 4 pillars holding up all the cantilevered area that collapsed. Those pillars are under a LOT of load, 40 years of salt and weather could have easily gotten through the concrete and attacked the steel beams inside. Only good thing to come of this disaster is that the mirrored building to the south that is still standing will give them a lot of clues as to what and how it happened.
Gut tells me it wasn’t intentional, but 3 or 4 kicker charges left against those pillars would cause what I’m seeing, and if there is a garage structure underneath those pillars would be exposed there and hidden from view as well. Hopefully there is security video in the pillar areas that can be reviewed. If it was intentional those charges would be muffled as well, at 1 a.m. on a Thursday morning charges set like that would be easy for people to miss when combined with the collapse right after.
Still going with my gut, salt spray and negligence is where my money would be.
Posted here that witness said garage went first then the rest of the structure.