Gods occasionally visit the mortal realm for particular reasons, such as certain festivals or to do battle against demonic forces in an invasion. In the case of the latter, a god has to be careful about controlling his divine energy. When gods fight on earth, they are required to keep their power levels low, and only escalate when absolutely necessarily. This is because they can accidentally cause natural disasters, or destroy the particular plane entirely.
The gods are so powerful that their human forms cannot completely contain their divine energy, which constantly oozes from them. Too much of this can be fatal for mortals. In one particular case during a battle between a god and a powerful demon, the deity lost control of his energy and flash fried an entire city. This city contained 50,000 inhabitants, who all burned to death in an instant. However, what is peculiar is that the bodies remained where they stood in the position they were in before death. The city looks like a place frozen in time, where you could see what people were doing right before they died.
As you can see from the write-up, I am trying to recreate a situation similar to Pompeii, the roman city that was covered in ash by a volcano and killed all the inhabitants. Instead of freezing people in the poses they were in with ash, Divine energy left a city of charred corpses frozen in time, still burning years later. How can I recreate this effect for this particular scenario?