More than 9,000 firefighters have been sent to fight a forest wildfire that broke out in north China's Inner Mongolia Autonomous Region at midday Tuesday, local authorities said on Wednesday. 

According to the regional forest fire prevention headquarters, the wildfire in Bilahe Forest in the Greater Hinggan Mountains had engulfed about 10,000 hectares by Wednesday afternoon. 

However, weak winds and relatively lower temperature made it easier to extinguish the wildfire, said Li Shuming, deputy head of the State Forestry Bureau. Twelve airplanes were dispatched to transport more firefighters to the southern regions.

A preliminary investigation showed dumping of burning stove ash by residents in open air caused the fire.