are going to be focusing on is why did this building stand for 40 years, and then collapse, suddenly, just this morning? you know, why -- what changed? what changed, in the condition of the structure? what changed in loading and other-environmental factors that were impinged on it? we've heard a lot, today, in the news about some of these potential changes. we've heard about deterioration. reinforcing rusting and the concrete. that, certainly, should be looked into. could've been a factor. we heard about settlement of the foundations that, perhaps, could have been a change factor. had there been alterations of the building done, over time? we don't know. was there some, extraordinary load on the structure, recently or at the time of the failure? we don't know that. >> what about gas? >> ga -- an explosion with gas?