What happened? How do I get rid of this eerie feeling?

Okay so I went for a walk in my local park and there are these like other paths that not everyone knows about and you have to go through this like gap in the fence to get there (I've been before) anyways I saw this 7 year old girl going up to the gap in the fence and no parents and she was really haunting/creepy looking, she was wearing this white frock gown dress type thing what you'd imagine a psych patient to wear back in the day or what a ghost would wear then she looked around to see if anyone was looking at her then she went in there and if you're thinking it was a hallucination it wasn't because shortly after she went in there two guys about my age (19) came out and saw her too and were like that girl is like 7 and she looks so ghostly and why did she stare at us with such a blank stare when she walked passed us and they were basically saying how they also got a creepy feeling from her. I don't know why but I felt kind of scared and still kind of do so how do I not get scared and what was she doing anyways?