"It [WTC 2] started exploding," said Ross Milanytch, 57, who works at nearby Chase Manhattan Bank. "It was about the 70th floor. And each second another floor exploded out for about eight floors, before the cloud obscured it all." [ASNE] "I saw small explosions on each floor." [Wing TV]

"It actually gave at a lower floor, not the floor where the plane hit, because we originally had thought there was like an internal detonation explosives because it went in succession, boom, boom, boom, boom, and then the tower came down." [Ed Cachia - Firefighter [Engine 53]]