You might remember the Brazilian television program's fake elevator prank I posted a little over two years ago at this link. Here's an even more elaborate one from the same folks, this time apparently done with the cooperation of a subway system.
As with the elevator version, the lights flicker off, and when they come back on, there's a pale little girl in white dress standing there holding a dolly, with no obvious place she could have come from. Then the little girl screams, and grown men cower (or, in the earlier clip, flee from the elevator at a run with the little girl and her dolly in hot pursuit).
This reinforces the impression I formed watching the tricycle scene in Stanley Kubrick's adaptation of Stephen King's The Shining: Little girls are just scary.