Noticed
At first, the man had been walking behind this young woman. However, it looked like he decided to change their positions after seeing that they were not the only people in the area. While this was not exactly a red flag in and of itself, the girl did something that made the boys feel worried for her safety.
Stop To Check
The boys were already getting ready to leave the underground parking garage, but something made them stop before they could do so. They decided that they needed to see if everything was all right and if there was a problem. But what exactly did they see that made them do such a thing in the first place?