Aliens

I can still taste the dust that filled my lungs as those Things continued down the line. One of them walks up to the person on my left, and utters this atrocious sound. The man next to me crumbles to the floor. The Things, I assume, are angered at this mans weakness, and proceed to attack the man. Blood splatters on my cheek.
This is the end. I know that once these Things decide to test my strength, I will accept the same fate as my former neighbor in line. They finish him. Blood from his body slowly drips down my cheek, but im too afraid to wipe it away. For some reason, I am to afraid to even vomit.
By this time, my lungs were now filled with ash, and that plus the shock from all the events occuring around me are enough to make me....
Black out.
"Guhh!" I gasp for air as I bolt up. But unfortunately, my nightmare is not over. I pay no mind, and continue attacking the air in order to fill my lungs. After a minute of doing this, I build up the courage to look up and see where I am.
My house.
But, if I am in my house, why does everything feel so odd?
"Mom!" I yell
No answer.
"Mom!" I yell, even louder.
Again, no answer. I look out my window, everything is just normal.
"A dream. My god." I have never in my life been more afraid of a simple dream. But it was just so vivid. I have to shake it off. Then I hear it, three knocks at my door.
Knock.Knock.Knock.
"M...Mom?" I say.
Knock.
"Mom?!"
Silence.

Despite everything that consumed my mind, I knew that I would never escape my horrible feeling with out someone to consult to. I decide to open the door.
Nothing.