MarkT:
I suspect the fire officiers usually want to turn OFF all the fans to stop fire spreading, not "clear the smoke" (ie fan the flames)!!
It's the smoke that does most of the killing (no oxygen, toxic fumes, total disorientation so you can't find your way out), not the flames. That's why tunnels have those massive exhaust fans: to get rid of the smoke in case of a fire.
Clear the smoke, give people air to breath to stay alive and get out, when that's done you can deal with the fire itself.