They are Chinnooks and if not mistaking ARNG. I miss seing the F-16s. I lived 3 miles away from SANG back in the 70's and remember the F-4s. They were awesome to see.I assume you're knowledgeable as to what VHF & UHF ATC freqs are used for the airspace over your domicile. If you'd heard the Chinooks talking with ATC & gotten their callsign(s) it probably would have at least lead to the unit that operates them. Then you could call that unit's PAO & assert your right as a taxpayer to be briefed on their mission.
Does Selfridge still have an AASF? If they were Chinooks, they're Army/ARNG. If they could have been CH-46s, they'd probably be USMC but I understand the USN might have some as well. Canadian Forces also have some Chinooks, and a model called the Labrador that looks similar (but usually they're bright yellow, used for SAROPS).