escalator and into the ticket hall, incinerating everything in their path. >> this thing is like a monster. >> there was just a complete rush of thick, black smoke from the subways, and it was right at that moment we realized that a flashover had occurred. >> flashover is a virtually instantaneous spread of fire. everything flammable ignites simultaneously. >> so, from two minutes, it had gone from apparently the size of a cardboard box to a major disaster. >> firefighters tried desperately to get inside the station but are driven back by the intense heat and smoke. >> firefighters were collapsing left, right and center. the heat down there had made some of them urinate themselves with fear. and when they came out to the top, they weren't capable of moving again. a lot of them were collapsing into heaps. >> ron lipsius stumbles into the chaos outside, and for the first time, realizes he is badly