Vague Setup but Interesting Plotline!
This is such a cool concept!! At first I did think werewolves because of the constant night and moon being out, but after realizing that the moon gets eclipsed, I realized it had to be vampires. That being said, there are some kinks/plot/environmental holes to work out otherwise. Lunar eclipses may only happen when the moon is full, how does your version of Earth account for that? I would have liked to see more world-building/ in-depth exploration of this constant-dusk environment. What does the sky look like? How does the community generate energy? I saw you mentioned "The Authority", is that post-earth's-nightfall's form of government? What happened there? You have a huge opportunity to provide a ton of details to really immerse your reader into this kind of post-apocalyptic world.
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One more aspect I would focus on is showing instead of telling! I would have loved to read how MC feels when these things are happening. While I can imagine, I'd love to have the insight of being in MC's mind.
There may have been a few awkward diction/flow choices or grammatical errors in here but they don't impede too much on following the story. However, I would say that attending to them might definitely help your reader immerse themselves in this world you built.
That being said, the questions you draw on to lead the reader through the plotline (as far as the first 3-ish chapters are concerned), are great for getting the reader hooked! Like who are these people, what is happening, and I'm eager to find out! This does play out like a pilot of a Vamp TV show (that I always have the guilty pleasure of watching) and I love that the type of drama encased in those shows is delivered well in these chapters.
I love this and the concept! And I'm excited to see how you further build upon it. I'll probably continue to read it in some spare time just to see what happens, haha. Cheers!