murrah building creating a 30-foot wide, eight-foot deep crater and the equivalent of a 3.0 earthquake. overall, 324 buildings in a 16-block radius are damaged or destroyed. >> i thought first, well, maybe we had a natural gas explosion. but if it wasn't that, maybe we had an earthquake. and if it wasn't an earthquake, maybe a plane hit the building. >> but investigators quickly determine the cause of the massive destruction. >> the fbi, we are told now, has confirmed that it was a bomb that caused this explosion. >> this is one of the critical. >> millions around the world watch and wrestle with the mystery of why such a quiet midwestern city could be the target of a terrorist attack. >> it's a pretty all-american, average city. so you think, why here? why on earth would somebody do something so vicious in the middle of the heartland? >> up to that point, nothing like that had ever happened in the united states. >> as soon as we get an ambulance here, we'll have you in the air, all right? >> immediately after the bomb went off, there were commentators all over this country saying, you