In Which It Was Needed

As they were leaving the building, she cried, "Let's go, Mistress Lisa!" at the top of her lungs.

After getting to her feet, leaving the room, and going outside onto the deck, Lisa instantly sat up straight and let out a big sigh. After that, she went outside onto the deck.

Lisa said something beneath her breath that sounded like "Oh, dude."

Given that there was no sign of life and the corridor was completely devoid of anybody else, it appeared as though she and Mona were the only two people in this white corridor who were still alive. This is because the corridor was completely devoid of anyone else.

Because of the circumstances, it gave the impression that they were the only two persons still present in this white corridor at that particular point in time.

According to the impression that it gave, they could have been the only people in the area at the time.