“...reported sounds similar to explosions...”
Hmmmm.
So... sonic booms?
It's too bad ordinary people on the street don't have some sort of mobile electronic devices they could use to actually record these alleged "explosions" and broadcast them to the world!
Regards,
“Noises of explosions” could be a distant artillery barrage. Heck, the artillery duel prior to Pickett’s Charge could be heard 100+ miles away in Philadelphia. Sound travels in strange ways and varies with atmospheric conditions that can cause it to bounce of the topography and travel very long distances.