CAFÉ: Vanished

The purple light only lasted a few seconds, but when it was gone, something was *definitely* different, because everyone in the room, except for Dawn, was gone. They had vanished into thin air. Their plates of food were still sitting on the tables, but every person was gone, just *gone*. Dawn ran around the café, looking into every possible place where someone could hide (the eating area, the kitchen, the bathrooms), but she really *was* the only one there. What had happened?