A brush fire is probably not as bad as a forest fire, but the heated air would kill you all the same.
Helped fight a small forest fire one time. I was amazed how fast a fire moved when crowning! Several people had to jump in a nearby river to escape the flames as the fire was moving faster than they could run. When we got back from our shift our pants/shirts had small holes and marks from the burning material that was being moved around by the wind.