A 3-D implementation of the finite-difference time-domain (FDTD) method is used to model 100-1000-MHz radio wave propagation in a generalized office building. Fire within this building is modeled as a cold plasma medium. The presence of fire is found to decrease the sector-averaged received power by up to 10 dB. The FDTD results also showing propagation through fire can introduce rotation in linearly polarized signals, increasing the power of cross-polarized components. Uncertainties in the plasma properties are modeled using nonintrusive polynomial chaos, and can introduce up to +/- 8 dB variation in the sector-averaged power.