Joshua 8:20-21 NIV

20 The men of Ai looked back and saw the smoke of the city rising against the sky,1 but they had no chance to escape in any direction, for the Israelites who had been fleeing toward the desert had turned back against their pursuers.

References for Joshua 8:20

21 For when Joshua and all Israel saw that the ambush had taken the city and that smoke was going up from the city, they turned around2 and attacked the men of Ai.

References for Joshua 8:21