'Smoke' in the Bible

Then the men of Ai looked back behind them and all of a sudden! smoke from the city was rising into the sky. They were unable to run in any direction, because the Israelis who had fled toward the wilderness had turned around to attack their pursuers.

When Joshua and the entire fighting force of Israel observed that the men who had been in ambush had seized the city and that the smoke from the city was rising, they turned around and attacked the men of Ai.