Most office buildings have walls with steel studs or steel supports, clad with gyprock or plaster over metal mesh. If any of these offices were remodeled in the past 25 years, they would have had to have fire blocking and double Firerock on the boundaries of the office space and the hallway and fire doors. Building codes require this to contain fires to one area on a floor.  Fires need fuel and oxygen, Hot fires need allot of oxygen, which usually is consumed quicker than it can get to the fuel.