Wouldn’t there have to be about 600 shell casings in his room if he were the lone shooter?
And I don’t quite understand the two windows thing. The two broken windows in the picture seem to be from rooms rather far apart. Was that one room?
Each floor has three arms or spokes. At the end of most of the spokes is a large suite as big as two or three normal rooms. The suite 'turns the corner" at the end of the spoke.
One of the earlier threads has a typical floor plan. He wanted two firing vantage points as described in some books on the subject.