But the last jet that hit the last tower, it wasn't a skyline plane, it was more of a combat jetflight. It was only a 2 seat fighter jet and it fired missles not bombs. If you watch and research like I had to at school, it shows that the last jet had a symbol of a fighter jet would. It fired 2 missles 3 seconds before it came impact with the tower. If you do some mathmatic science, that would be about right for it to fall. The way they constructed it and how the jet shot the missle 3 seconds before it went threw it, it would fall.
As for the first hit, when the jumbo plane crashed into the towers, the fire that bursted out hit one of the generators/fuel tanks in the building that caused a huge fire explosion take place
I did a 2 month research for my history class from August-September.