I saw the Van Drew bit. Occam’s razor and all that.
Three possible options:
1. Hobbyists/civilians/whatever. Seems too expensive and would involve too many people, some who likely wouldn’t be able to keep their mouths shut.
2. U.S. military experiments/training. This has some possibilities.
3. A foreign entity or entities (Iran and China?) with a controlling “mothership” (an unfortunate term likely to engage the conspiracy folks) in international waters.
In order, and if I had to put odds on the options, I’d say, respectively, 5%, 35% and 60%. Would the military really test over such populated areas?
If the latter of the three options, blast the drones from the sky.