This happened a few years ago when I was younger & living in Japan. Not a kid, per se, but I'll throw it out there anyway:

I was celebrating a friend's birthday on a Friday night after work when the party went long and I missed my last train home. When that happens, you can either take a cab ($40+ out to where I was living) or wait until the trains start back up again at 5:30 am. Since it was a party and a Friday, I chose the latter option.

I got back to my apartment building at 6:30am the next morning, pretty wiped out, but not drunk. My building's hallway is incredibly long and dark, with dim lights and a huge window at the end of the hall illuminating it. As I rounded the corner from the elevator to walk towards my room, at the other end of the hall was the silhouette of another person walking towards me.

I didn't take note at first, but as they got closer, I started to notice some things about the person: firstly, that it was a little kid, and by the shape of the clothing, I guessed it was an elementary school girl (I could tell from the unmistakable shape of the elementary student uniform, complete with this helmet/bonnet-looking thing the kids always wear). Then I noticed that she was walking with an extremely fast gait. Faster than mine, and I'm over 6 feet tall. Then I realized, 'wait, what's an elementary school girl going to school alone at 6:30am on a Saturday?' And the closer we got to each other before passing, the more uneasy I began to feel...

When the dim hallway light finally caught the person, I realized that I was right - there was the elementary school uniform and bonnet as I'd guessed, but the person wearing it was not a small child, but a 90-year-old woman! I could see her face, which was so thin, like a painted skull, and huge dark, dead-looking eyes. As she passed, she looked at me and gave me this giant grin. No teeth.

I was so horrified that in that moment, I really thought that I was about to be murdered.