They have been flying army black helicopters out of Conroe for many years. I believe it is a Guard unit stationed there.
Do a google maps search on these coords and you will see them 30.345986,-95.424511
I have never heard of a live fire or dummy fire drills in the Houston area.
They've been doing them up north in random towns for a few years now. It may just be starting to trickle down here. Or it may just be them getting ready for an invasion. All I'mma say is they don't have nearly enough personnel to try and use our military against us as a country. Hell, we can't even go into another country and lock it down due to us not having enough equipment/personnel.
I think they're just practicing for if one of our cities comes under attack from an outside force. I don't know about y'all, but prior to 9/11, I can't think of any time that we've practiced for such a scenario.