Fire broke out Thursday in a forest in southwest China's Yunnan Province, local authorities said.

The fire began at 3 p.m. in the Xiaocaoba tree farm, which covers 180,000 mu (about 12,000 hectares) in three counties, according to an official in the forestry administration. The cause of the fire hasn't been determined.

About 1,000 mu has already been burned.

More than 1,000 people were battling the fire, which was being fanned by high winds and a 28-degree Celsius temperature. Flames were leaping as high as 20 meters, the official said. The heat from the blaze could be felt hundreds of meters away.

As of 9 p.m., no casualties had been reported.

(Xinhua News Agency February 13, 2009)