I really liked this. Basically, its the kind of story that I'm always looking for and no one writes them, though. So, yeah, it's going to my faves. Great job

This story is pretty retarded. So what, a girl that goes into an empty school at night? The plot itself is stupid and awkward...no offense. Yeah, creepy indeed, and also crappy. The echoes were not scary, they were stupid and jumpy. I don't know if it's just me, but I shuddered because the echoes were not taunting and they weren't really required for the story. I think you were drunk or smoking pot when you wrote this. Hey, wait, do I sound like too much of a bastard? Hey, I'm just reciprocating so deal with it. Anyway, I guess itw as sort of ok, but I didn't enjoy it much, because it was boring as hell.

Conclusion: Please don't hate me for this, but...you suck. (Ouch)

X-Eragon-X

(Have a nice day!)

were is the rest I can't wait to see what's going to happen a few errors though but it doesn't take away from the readers. please upload soon.

Who's the strange eerie, repeating voice? It kinda well annoyed and freaked me both. Love the name Adrianna!

Really. Creepy.
I really liked this piece, honestly. So, with that said, please keep in mind I am not trying to belittle your writing. A few positive things first:
You clearly know how to use a spell-checker! That may sound trivial, but it puts you leaps and bounds ahead of a great number of folks on the website. Thank you for showing your appreciation for me as a reader.
You built up tension really well. I was really creeped out and had terrible visions that reminded me of the movie The Grudge. I think the English version comes out in theatres soon and I recommend seeing it because you just might like it. That isn't to say your story is "just like the Grudge" (it isn't), but that it had some very good moments of terror.
Finally, I did enjoy your writing. All the things below, while there are a lot, are minor things that are admittedly hard to avoid without really going through some scrutiny. Your writing is by no means BAD, it is actually pretty GOOD, and by working with the suggestions below you can better it in leaps and bounds.
That said, I think the ending is a little too ambiguous. The entity ended up possessing Adrianna, am I correct? In any case things need to be clarified a little better because the transition between:
"'Thank you. Thank you. Thank you..."
and
"Adrianna stuffed the remainder of her clothing..."
needs to be a little less jarring. I don't know what to recommend at this point (I am rather sleep-deprived) but that is my biggest recommendation. I can only guess at what happened at the ending, when I should KNOW.
Otherwise, onto the grammar!
"The SOUND continued. Adrianna squinted her dark green eyes for the location of the SOUND, but it seemed impossible to pinpoint its location."
Can you avoid using sound twice in such close proximity? "Noise" perhaps would be a decent substitute for either one. Also, say "...it WAS impossible to pinpoint..."
Eschew obfuscation, as they say, which is a smart-alecky way of saying that your writing should not make use of almost's and maybe's. Be specific, be definite.
"It was a loud, wailing sound, ALMOST screaming."
Say "like screaming" or something similar. "Like" is a similie, "almost" is obscurity. I will list the other wishy-washy points below, and my recommended fix is in parenthesis. Feel free to use your own if you have a better one.
"She had tried to ignore it, sleeping in her parents bedroom, but she SEEMED TO BE (was) the only person who could hear it."
"The sound SEEMED TO DRAW (drew) closer as she headed across the street, toward the elementary school that she had been attending for the last year."
"The sound SEEMED TO REMAIN (remained) unchanged in the midst of the school, as if it had completely enveloped the area."
"They were pale, bare, (feminine) feet THAT SEEMED TO BELONG TO A WOMAN."
"The light SEEMED TO BECOME (became) even brighter, blinding Adrianna."
I know it's a pain. In all honesty I do it a lot in my own writing, and the folks in my writing circle are always quick to point it out for correction. It improves the quality of your writing a great deal just by removing them.
Also, you use "sound" a lot. As I suggested above, break it up. Go to w.thesaurus.com or use a print one, but use a different word occasionally. But, as you are looking through the thesaurus, avoid words that are too obscure or scholarly, like this:
"The sound disappeared into the midnight ATMOSPHERE."
You can just say "air". Atmosphere sounds far too scientific to be used in this situation, and it really jaunted me when I read it.
Adverbs. Avoid them where you can. In most cases, if you find yourself describing a verb using an -ly word, chances are you can just use a better verb in its place. This is something else I am always guilty of myself. I will give a few examples in your work and leave you to figure out the rest:
"Dimmed lights hummed DULLY (just drop this) at the entrance, ..."
"QUICKLY, she turned around and pushed hard against the door, ..." (Just say something like "She spun around" or "whirled around")
"She stepped back and BREATHED IN SHARPLY." ("sucked in her breath")
"She HELD ON TIGHTLY TO (clenched, grasped, etc.) her bat and swivelled around."
There are others. Not that you should NEVER use adverbs, but most of the time you should avoid them. If this sounds difficult to follow, trust me, it can be. If you ever fully figure this one out, let me know too.
One last thing.
"Adrianna clasped ONTO her baseball bat as firmly as she could with her small hands."
"She clasped ONTO the handlebars on the door."
You don't need the preposition "onto" in either of these sentences. "Clasped onto" makes it sound as if she is holding onto these things for dear life, quite specifically because she will fall if she doesn't. As her danger doesn't involve falling, I don't think you need them. Perhaps I am wrong, I cannot explain it better, it just sounds strange to me.
As I said, I know it's a lot, but your writing overall is pretty good, so the only way to offer suggestions for improvement is by getting really nitpicky.
Great work. Keep on writing!

This was a good one! Honestly, I didn't expect this piece to be that good because the title was not that attractive, but surely the piece makes up for that! I hope there's a part 2! :)
P.S. Please review my works also, An Untitled Piece of Eternal Love, thank you very much! :) Oh yeah, I hope we can be friends... :)