An interesting start.
If I might make suggestion? It might be desirable to break it up into slightly shorter paragraphs. Whilst what you have written is fine for a printed page, on a monitor screen shorter paragraphs are easier to read.
Also there are a couple of slightly cumbersome moments. The line "High above the darkness of the nighttime sky over Los Angeles hung in place." doesn't actually make sense, and the phrase 'high above' is reused a couple of sentences later.
Now when I started fan fic I'd found myself doing that sort of thing all the time. I attempt to prevent it by writing it in wordpad, saving it, leaving it for a while then reading it with fresh eyes. I'd then make any adjustments I need to before posting it.
Please don't be disheartened by my comments! I'm eager to see how this story develops.
There is some good descriptive work here, particularly the John vs. 7T fight. Keep it up!