Thanks to all you guys for the info; it seemed so unusual to hear & see something like this after dark.
I was just amazed to hear & see them in the clouds, & could only see the strobes--but I suppose they may not even have other lights.
Also the noise was something I have never experienced before but you could tell they were maximum "on it"
Buckley is nothin'. A real active AFB that does training 24-7 is a sight and a sound to behold. Buckley is a big data center with a leftover Air Guard habit from its days as an ANG base. Haha.
Without getting into it too heavily, or even touching on the secret stuff, look at Front Range military bases and their commands (tasks), from just the public information, and realize they're all connected -- literally connected -- used to be with AT&T microwave towers (they're all still standing but the feed horns have long been taken down by the current owners), nowadays it's fiber optics -- and Buckley's real value in the modern military in Colorado is easily figured out without much effort.
It isn't flying aircraft.
All you're seeing at BKF is the bare minimum of flight currency and training for the ANG (F-16s) and the Army Guard (rotary wing stuff, usually pounding along eastbound out around County Line Road and far more active at night than the ANG guys and gals).
It's not what I would call an "active" AFB as far as Air Ops goes. Pretty quiet really.
Active" as in meeting their actual mission? Very. The gates are busy at shift changes.
Anyway back to the aircraft... if they follow the usual ANG training patterns the evening/night stuff will last a couple of weeks, and return again at a similar time next year, barring new budgetary constraints. When they're not on a night training schedule,
Saturday mornings on "Guard weekend" each month, are often an excellent time to watch the F-16s head southeast to train (most Military Operations Area airspace in Colorado avoids DIA like the plague, and is south and east of the Denver area. They will usually depart the area and start their climbs near E-470 and Quincy or Smoky Hill.
It's also a fairly convenient and secure place close to the city to park AF1 during fundraising dinners and photo opportunities.

Easier to secure and less disruptive to the airspace than parking it at DIA.