The windows broken out were an escape route to the roof. Looking at the scene the window on the far right was the escape route where 3 guys on the roof dropped line(s) down to that window and the three guys in the room rappelled up to the roof with help by the other three.
They either used various re-entry routes off the roof where all 6 came down as suited up as swat and dispersed as the real swat was busy at the 32nd floor room.
It now appears there were operative(s) in the crowd yelling death tonight to the concert goers. This is way to obvious not a single guy did all this.