Whenever a player successfully attacks your Base or an Alliance Building, they will begin to burn and will lose defense over time. Consecutive attacks on your Base will cause more Buildings to burn, increasing the defense loss and total burn time (Buildings are randomly selected). A debuff is applied to each burning Buildings. The debuff negatively affects the functionality of your damaged Buildings even if they are not burning.
To stop the defense loss tap on your City Wall and tap the Defense button. You can Extinguish all fires at once by using the Free Extinguish (12 Hours Cooldown after its used once)