Everyone has a different perspective

I thought that we actually happened, but then I woke up...

Someone is killing. Every time the light goes out. Every time the light comes back on, another is killed. My names Cassandra Mongrel, and I don't even know if I'm next. Just as quickly as the light comes on, the murderer vanishes; vanishes like it came out of thin air and can easily get away. Who's next? Why is this happening? Will I survive this dumb night? Or.... Am I the next one?