Dream made me have an anxiety attack at school...

I am really affected by current events happening e.g. Syrian air strikes, school shootings, and, local emergencies(e.g. there have been kidnappings near where I live).

So recently I have been dealing with a lot of anxiety attacks and break outs during class, even though I am not stressed or have a lot of work. So a few weeks ago I had a dream about a school shooting happened at my high school. So I was in a classroom, which is an actual one in my school made out of glass, and I hear the emergency bell and we all hide. Once I figure out I’m in a dream I leave the classroom and go out to the field. There I am following the shooter until I forget that it is a dream. Then, the shooter approached me and put this huge shiny grey gun at my head. He pushes me to the ground and stars reciting the Bible. He finishes a verse and I say ‘amen’. He takes the gun off of my forehead and my dream ends.

Let’s skip to a few weeks after this dream. My school was having an “emergency drill” to teach us how to hide. Then, while hiding I suddenly couldn’t breath. After the drill is over I leave the classroom and I’m fine, I was scared though. Later, during lunch, the smallest thing just triggered me and I started crying during lunch. I whispered to my friend, “I think I’m going to have an anxiety attack” and I leave. I couldn’t go to any more if my classes and for the rest of the day I wasn’t able to do anything.

Please someone tell me what this could be.