Sodom and Gomorrah were two ancient cities mentioned in the Bible most likely near the Dead Sea. The story in the Bible says that the town was destroyed by "God" because of the their "wickedness" by fire and brimstone (sulfur rock). So what does science have to say about this story?
As we know much of the Middle East sits above oil and natural gas fields as well as atop pockets of sulfur rock or brimstone. There are fault lines in the area where most scholars believe Sodom and Gomorrah existed as well as within much of the "Holy Land." Ancients didn't know much science and therefore natural disasters would be seen as "God's" doing and explained by man's "sinning."
So all it takes is a decent sized asteroid to hit the area, which would ignite the oil and natural gas fields nearby and underneath the city. As well as the igniting and throwing sulfur rocks into the air, which would then reign down upon the nearby cities of Sodom and Gomorrah. Thus giving off the effect of flaming rocks pouring down upon the cities and burning them to the ground.
Another explanation could stem from the many fault lines that exist in Israel, Jordan and throughout the Middle East. An earthquake could have cracked the Earth, which exposed natural gas pockets, pools of oil and veins of sulfur rock. All it would take is one spark from the many cooking fires to explode the pockets of gas, ignite the sulfur rock, which would reign back down upon the city burning it to the ground.
There are simple, (Occam's razor) scientific explanations for this event either way and so people who were not privy to science would seek to explain such a natural disaster with what they believed--"God." "God" was an understandable way to explain events, which were at the time mysterious in origin and thus very frightening.