Joshua 8:17-21

So not a man was left in Ai or Bethel, but they had all gone out after Israel, and they left the city unguarded and pursued Israel.

Then the Lord said to Joshua, “Reach out with the sword that is in your hand toward Ai, for I will hand it over to you.” So Joshua reached out with the sword that was in his hand toward the city.

Then the men in ambush rose quickly from their place, and when he had reached out with his hand, they ran and entered the city and captured it, and they quickly set the city on fire.

When the men of Ai turned back and looked, behold, the smoke of the city ascended to the sky, and they had no place to flee this way or that, for the people who had been fleeing to the wilderness turned against the pursuers.

When Joshua and all Israel saw that the men in ambush had captured the city and that the smoke of the city ascended, they turned back and killed the men of Ai.