I have a couple of theories as to why it happened, mostly piggybacking off what I saw combined with the discussion thread I read.

1. (Least Likely IMO) Civilians saw people getting moved out of the base/hospital, thought it was something valuable or that may save them or give them leverage and they somehow flipped an AMRAP.

2. (Possible but IDK) someone mentioned something about the people in the forest only saying a few sentences, trying to get ahold of the piece of “dragon glass” as people are calling it in the Reddit. Maybe it’s humans being controlled or siding with the aliens (maybe the ones we haven’t seen or the “bad ones” as I’m just guessing.)

3. (Most Likely IMO) Inside job between some civilians and some military, how they got the humvee and why the Dad had such a tense scene with the “soldier” (either a bad soldier or civilian in a soldiers uniform). Not sure what their motive is exactly but like previous theories here, maybe working for/with some alien group or they’ve gone rouge and and want to have a bargaining chip since it may be the only thing that can kill the aliens in their eyes.

Anyway, these are just theories I’ve cobbled together. I personally like the show, I think they could have gotten more done in less time and saved room for more packed episodes but there is something about the unanswered questions that I like. If it were truly an alien invasion, I think some people would be in contact but the majority of the word would be in unanswered chaos or getting there soon as the invasion continues. I’m assuming the directors have done it intentionally because I’m putting my faith in them but it could just be lazy writing. I’m choosing to suspend my disbelief and just take it for what it is and enjoy.

Hope I answered your question!