Or the person sending the light flashes might have won the fire fight, against soldiers or looters.
Or, he was shooting at zombies.
You know I kind of have a emergency bag but my danger is weather related (others may live in earth quake zones, etc).
I think I will print myself up a Morse Code guide and laminate it for my kit. Maybe tape it to the outside of an Altoid tin can.
Semaphore, too.