HOHHOT, June 4 (Xinhua) -- A total of 4,320 police and fire fighters have been sent to battle forest fires in north China's Inner Mongolia Autonomous Region, local fire authorities said Monday.

A fire, which broke out on Saturday in a forest in the northern area of the Greater Hinggan Mountains, had been extinguished as of Sunday night.

However, another fire in a national nature reserve that was discovered on Friday is still burning, and has spread to neighboring Heilongjiang Province due to intermittent gales.

Ongoing high temperatures and drought have increased the risk of forest fires in the mountains. Helicopters and large fire fighting equipment have been deployed.