This doesn't look like flares to me, certainly not ones that would be fired from your 'standard' flare gun kept on a light aircraft.
These smoke trails, whatever they are, also extend quite a way into the distance, whereas your average flare will travel around 500 feet up into the air and fall slowly back to earth.
These also look too big to be associated with the size of aircraft we're talking about here.
That being said, I hope they do provide authorities with some kind of clue.