The fire in the city was a byproduct of Jhonny simply being Jhonny.
Initially, the man had not planned on burning the city to a crisp at all, but as he wondered around on the streets of Dombivli, he was excited to see a lantern shop and decided to visit the place.
The lantern shop was in the middle of the market Street and what the local authorities did not know was that, besides manufacturing lanterns, the shop also sold fireworks illegally and had a stash of it stored in a hidden chamber beneath the floor.
When Jhonny entered the store, smoking a cigar, the shop owner instantly requested him to put it out, and unlike normal people who would use Ash trays to put out their cigars, Jhonny just stubbed it against his palm with the burning Ash trickling down the cracks of the floor and igniting the gunpowder stored underneath.
*KABOOM*