The concussive thuds not from the shells are not people shooting off illegal fireworks - the explosions were from the lift charges propelling the shells into the sky during this display of pyrotechnics.
"The Battle Hymn of the Republic" is the final song in that Independence Day pyromusical, building up to the thunderous fireworks grand finale Itasca ever has seen in this 4th of July celebration-bash........
The ending of the "Battle Hymn of the Republic" was drowned out by the finale of the explosions. But for some people, some people like the explosions than the music.