Strange Sound

My friend was coming out of her office and heading to her car, when suddenly she heard a weird sound from the parking lot. It was neither the sound of an animal nor a human being. Wondering what that could be and being cautious, she slowly moved to her car. Somehow she reached the car, but still couldn’t figure out from where the sound came. Her mind was imagining many things about the sound and she slowly started to get into the car and as she was about to leave, the security guard’s mobile phone was ringing with that weird sound!