The sound of the siren and the magic sound can be heard from the hallways. An intruder.

Nacht, the "intruder", was walking through the hallways as his demons killed the scientists.

He stopped when he was in front of a door, he put his hand on the handle as he opened it.

Nacht opened the door as he saw a kid, you, laying on the floor, unconscious with blood on the floor dripping down from your head.

He assumes you're one of the experiments considering the number on your neck.