During the Oklahoma city bombing, people remarked seeing small explosions inside of the building.
Strangely, the same demolition company which was contracted to clean up the rubble in Oklahoma also "cleaned" up after 9/11. That company's name is Demolition, Inc and as its name clearly implies ... specializes in controlled demolitions.
Demoliton, Inc was also in charge of exporting the rubble after 9/11. This was done so hastily that no investigators were able to perform any tests on the rubble. Had explosives been used, trace residues surely would have been found.