The rows and rows of buildings all sort of balance each other out and give the photo a really level feel, even with the smoke rising to the sky off to the side.
The lines on the ground and the people on them diagonally lead to the man in the bottom center of the photo who might be giving some sort of mourning speech, making him the main focus.
The ruins of this falling building to the right lead ones eyes towards where it might fall, where you would see the firemen walking in a line trying to find lost victims, whereas you would not notice them as easily if the building were in the center of the picture.
You can really only focus on this sad, crying woman when you look at this picture and the flag she holds because there is nothing to distract you around her.