A helicopter fights the fire which broke out Tuesday in a forest in Baoshan City, southwest China's Yunnan Province, March 8, 2011. [Photo: Chinanews.com]

The initial investigation into a fire that engulfed 400 mu (26.7 hectares) of a forest in southwest China's Yunnan Province indicated that arson was to blame.

Police say a mentally ill man is to blame for a forest fire in southwest China's Yunnan Province that raged for a day before being extinguished Wednesday morning.

The man wandered into a forest of Baoshan City and lit a fire with his lighter around 11 a.m. Tuesday, local police said.

It quickly spread engulfing 400 mu (26.7 hectares) of forest and threatened a 300-year-old Buddhist temple nearby.

Around 1,500 people and one helicopter fought the fire which was put out by 8 a.m. Wednesday.

No causalities have been reported, and the fire did not damage the temple.

About 3,000 forest police officers and soldiers battled the fire, with a helicopter joining them.