Hope there is not a dirty bomb, or worse involved in this.
Hopefully there's not more attacks to come.
I don't think they have a clue how many people could be trapped underground.
I've always thought that AQ had no idea the towers would fall. Casualties would have been much lower if they had stood. I also believe that it's gotten harder for AQ to pull off a spectacular attack like 9-11. We know now that 9-11 was years (maybe a decade +) in planning. Since then they've been on the run and their money and other networks have been seriously damaged.