That she made an error. The simple explanation was that she [and other reporters] were told that WTC7 looked like it was going to collapse, so they made sure emergency response were not near that area. She misreported that it HAD collapsed. Simple human error. I think that's a whole lot more plausible than "we are going to pull it, but don't report this for 20 minutes because we haven't done it yet, and don't tell anyone we are doing it because we want to make it look like part of the terror attacks".