"I deliberately omitted details about the situation from the photo's description to let people try and figure out what's going on. So, spoiler alert: What you see is basically a firework's misfire where it blew up on the ground instead of taking off into the sky. (No one was injured, and it might even have been a deliberate prank by the young men firing it - it happened twice during the 15 minutes I was there.)
"The exposure time for the photo is 2 seconds, which I had pre-set on my camera for regular photos of fireworks. Many viewers have speculated that the exposure would be a much longer one of many separate explosions, but that's just the fractal-like nature of fireworks and explosions - against a featureless background you can't really tell the size and scale of what you're seeing. So almost all those different lights are just parts of the same firework, and the result is a combination of luck and timing."
Kimmo Kuloveski's Flickr