Dream of building

I was in a large building, possibly an apartment complex, with a group of people. Everywhere I looked there were people murdered and murdering others. I realized that my only option was survival. As the dream progressed, I found myself killing others. My weapon of choice was a knife, but I had a gun as well. At one point, I realized that the gun didn't work, I could hear the knife sinking into the flesh of those I killed. I was killed at one point, but came back as if nothing happened. I woke after I drove my knife into someone's back. As I slept, I could feel my body shaking uncontrollably.