A fire department decided to blow up a New York Skyscraper and did it the same day! Can a building be loaded with explosives in just a day?

This is in reference to the trade center building 7 [aka the Salomon building] on September 11 in 2001.

Larry [the owner of the building] suggested to the fire department that maybe the smartest thing is to "pull it" [referring to blowing up up his building] and then he said that the fire department "...made that decision to pull and then we watched the building collapse..."

Here's a one minute clip about this decision:

https://www.youtube.com/watch?v=C3E-26oVIIs&featur...

My question is how can they load the building with explosives and set if off in a single day [it went down at 5:21 PM the same day]. And considering all the chaos happening all around there at the time how do you get the explosives contractors to do this in a timely manner? You can see here the fire department personnel directing people away from the building as it was about to be blown up:

https://www.youtube.com/watch?v=z9CXQY-bZn4

You can see that it sure looks chaotic near that building. I don't see how they could load it up with explosives on such short notice. Now here's a thought, maybe it could be that buildings are built with the explosives already installed so they can be blown up in an emergency. What do you think?