It would appear that a 'populated area' has experienced an unusual event, apparently loud jet sounds in various locations at approximately the same time for over one hour; what is also unusual is that there may have been more than one aircraft without active transponders.
It is unfortunate that the wealth of experience from within this forum has not chosen to offer an educated or reasonable explanation to this unusual event, rather we have previously been or are still active in ‘making noise’ that we may forget what it may be like to be on the other end of it.
I believe it was on Interstate 15 at Marine Corps Air Station Miramar there was (or perhaps still is) a sign “ JET NOISE THE SOUND OF FREEDOM” I understand it was to keep the local residents 'on side'