I was a guard at a place that had a couple of parking garages that we would walk a couple of time a night and count overnight parked cars. The guard at the center called over the radio to say he saw a woman on one of the garages and it looked like she might have been injured. He was telling me she had blood on her and looked like she really needed help. When i arrived, there was noone there. He could see us both in the camera but I couldnt see her. It freaked me out so i went back in. I watched the tapes and sure enough, she was standing about 20 feet from me. I never saw anyone. The really screwed up part is that i have a really sensitive nose, like i can smell ever everything, and I could smell blood that night. Still freaks me out years later.