Is it normal that i can't stop thinking about my own death?

A few weeks ago I had a dream that I was killed. It felt so weird. I was in like a store or something and there was a shooter with a shotgun prowling the store killing people, he finds me and I try to fight back, angering him, he shoots me directly in my chest (there was no pain, it just felt like pressure and weight in the area) and leaves me to die, I'm trying to get to safety but the edges of my vision are going dark and I can't breathe. Then I die.

The thought of my own death has just stuck in my head after that, for example, I was in the car and suddenly I just envision the car crashing and the seat coming down on my legs and smashing them and killing me. I recently just thought about being shot to death by a shooter during a thing I'm going to tomorrow.

I hate thinking about it and I just feel like I'm going to die.