9/11 fire-fighters: explosives in building, page-226

WTC7 was burning fiercely on 3 or 4 floors for a long time before collapsing.Towers 1 and 2 collapsed from the top to the bottom,a very rare way to demolish a building of any size.Someone posted that the tower on top of one of them collapse into the building before the rest collapsed,this has not happened on any video I have seen,though if you did not look closely, you could make this mistake.Happy confusions.