Judges 20:38 (KJV)

So the children of Benjamin saw that they were smitten: for the men of Israel gave place to the Benjamites, because they trusted unto the liers in wait which they had set beside Gibeah.

And the liers in wait hasted, and rushed upon Gibeah; and the liers in wait drew themselves along, and smote all the city with the edge of the sword.

Now there was an appointed sign between the men of Israel and the liers in wait, that they should make a great flame with smoke rise up out of the city.

And when the men of Israel retired in the battle, Benjamin began to smite and kill of the men of Israel about thirty persons: for they said, Surely they are smitten down before us, as in the first battle.

But when the flame began to arise up out of the city with a pillar of smoke, the Benjamites looked behind them, and, behold, the flame of the city ascended up to heaven.