The Hobbit, Chapter 14 question "Fire and Water"

When the watchmen see fire in the distance, they send out a warning, but their warnings go unheeded. As Smaug approaches, the people are in a state of combined worship and terror. Smaug breathes fire down upon their city but those who listened to the grim-voiced man had time to collect water to mitigate the damage. They also destroy the bridge that links the island city to the mainland and in this, they are able to halt Smaug's advance.