HOHHOT -- More than 7,700 people are battling a forest fire that broke out Tuesday in northern China's Inner Mongolia autonomous region, authorities said Wednesday.

The fire broke out in Beidahe forest in the Greater Hinggan Mountains. As of Wednesday morning, it had engulfed around 5,000 hectares of forest, according to the regional forest fire prevention headquarters.

Dry vegetation, strong changeable winds and high temperatures are making it difficult to extinguish the blaze, according to the headquarters.

State Forest Fire Prevention Headquarters are dispatching 12 firefighting airplanes to the site. Another 600 firefighters from neighboring Heilongjiang Province are ready to join the efforts if the blaze is not brought under control.

The cause of the fire is unknown.

This spring, temperatures in Inner Mongolia are higher than average, increasing fire risks.

A cross-border fire broke out in another forest in the area Sunday. It was put out and cleanup is underway.