I've taken a number of courses with Tom Perroni at Commonwealth Criminal Justice Academy. He's an EMT instructor, and he does courses including Combat Care Under Fire, Executive Protection, Force on Force, etc. One of the most memorable courses included using a "haunted house" made on another floor in his office building. It was right after Halloween, and the charity was done with it. It was made with plywood walls, painted black and the windows were all blacked out. An instructor, armed with a pistol loaded with Simunitions would hide, and a team of two went into the blacked out building with a flashlight and a pistol also outfitted with Simunitions. Until you have tried to clear a completely dark building containing an armed aggressor, you really don't understand what police have to face.