scene. i could have walked into the living room checking on them and found that rubble. and it just, i don't think i process it, i'm in that moment but i don't think i really processed what happened. >> the first class action lawsuit has already been filed against the collapsed towers building association. it asserts that the disast c clear -- disaster could have been prevented through the exercise of ordinary care, safety measures and oversights and seeks damages of more than $5 million. what do we know so far about this 40-year-old building. cnn's tom foreman takes a look. >> you're watching what some engineers are calling a classic column failure. what they say they'd expect of a building's key support column giving way. but did that happen here? where local officials say robust inspections are the norm. >> there had not been any concerns. >> this building was constructed