9/11 fire-fighters: explosives in building, page-21

also interesting to note:

PROFITS OF DEATH - INSIDER TRADING AND 9-11
Between September 6 and 7, the Chicago Board Options Exchange saw purchases of 4,744 put options on United Airlines, but only 396 call options. Assuming that 4,000 of the options were bought by people with advance knowledge of the imminent attacks, these "insiders" would have profited by almost $5 million.

On September 10, 4,516 put options on American Airlines were bought on the Chicago exchange, compared to only 748 calls. Again, there was no news at that point to justify this imbalance; Again, assuming that 4,000 of these options trades represent "insiders," they would represent a gain of about $4 million.

http://www.fromthewilderness.com/free/ww3/10_09_01_krongard.html