Firefighters have extinguished a fire that extended from Russia to primitive forest to the north of China's Greater Hinggan Mountains, firefighting headquarters said Saturday. As of Saturday morning, firefighters have started to clear up the fire ground. There was no smoke, flames and steam found on the ground, indicating that the fire is out, said the headquarters. A forest fire in Russia crossed the border Wednesday afternoon and extended to the Yimuhe Forest Farm run by Wuma Forestry Bureau in the north of China's Inner Mongolia Autonomous Region. Chinese forestry authorities mobilized 1,400 firefighters and nine helicopters, who struggled to control the fire in the undeveloped primitive forest late on Friday night. Covering 950,000 hectares, the primitive forest to the north of Greater Hinggan Mountains is China's largest undeveloped wildwood area.