More than 1,000 people are struggling to extinguish a forest fire raging in a nature reserve in Jilin province since noon Tuesday. The blaze broke out at 12:35 a.m. and it has destroyed more than 4 hectares of forest in the Changbai Mountain Nature Reserve, said Zhang Hui, an official with the provincial forest fire control headquarters. Three helicopters and more than 1,000 firemen have been mobilized to fight it, and now the fire is under control, Zhang said. The cause of the fire is under investigation, Xinhua reported.