Got a true story for you. I was told this when I went through EMT class by one of the speakers we had. He is a career guy in a neighboring city. He told me they were called to a house fire, and after extinguishment they were doing salvage and overhaul, and at every door was a steel cable, and on each end was a hand grenade. There were also holes cut in the floor. Amazingly enough no one hit the wires or fell in the holes. The holes they noticed while fighting the fire the wires they did not notice until salvage. Kind of makes you wonder what might be waiting for you on the other side of the door.