[concretebob]

If you are not familiar with the interior mechanical elements..i.e., HVAC, water lines, gas lines, hydronic piping, (heating water), of a commercial building, you can't know what will happen during an intense fire.
Lines already pressurized, will explode when heated.
Methane gas from sanitary waste-lines will explode.

[Calpernia]

I didn't realize that either. That does make sense too.

Thank you very much for that insight.