Pass It On! Writing discussion

The black and red colors of the sign on the door triggered a sense of unease, though the words were friendly enough. She called in a "Hello?!", but got no answer. Perhaps everyone had stepped out.

There were signs that many people had been there until quite recently. The lights were still on, the portals seemed to be in working order, and there was no dust. An old-fashioned terminal blinked a flashing cursor on an otherwise blue screen. A little note was on the keyboard. It seemed to be scribbled very hastily and had splotches of dried brown something on it (coffee? tea? blood?). It said, quixotically:

Only one sentence; more than one and they come for

She looked at the note carefully and drew back in fear.

she felt helplessness eat her alive, and didn't know what to do. "what does this mean?! ", she thought.