[BurkeanCyclist]

Yeah, I'd think that with all those cameras focused on the WTC, they would have picked up a third plane if one had been there.

[TERMINATTOR]

There may have been a ground based attack as well. Possibly a bomb. This is just speculation on my part.

[BurkeanCyclist]

I just saw a replay of the first tower collapse, and there did not appear to be a crash or an explosion at the base of the tower before the thing started falling.