Noisy Silence

It was a little after 7pm when I noticed that the office had become awfully quite, where mere minutes had passed since Jeremy walked out of the office door. In the silence that followed, the light on the walkie-talkie that was standing still at the corner of my table flashed red and a sound popped out. I started, knowing very well that there was no one else around.. so who had made the sound? I was pretty sure it wasn't any of the guys at work because the sound was rather soft, and high pitched at the same time, and as far as I knew they had all gone back to break fast for Ramadan with their respective families. This I ascertained when I saw the almost deserted carpark (and working where I do, I know which car belongs to whom, and none of the cars left were walkie-talkie owners) And it couldn't have been static either... that has a different sound. I was too unnerved to stay on further, all plans to work late flung out of the window. I knew it would only be moments before stuff would be moving noisily across the floor of the utility room right above the office, and I sure as hell did not want to be there when that happened.