BEIJING -- Chinese President Hu Jintao has ordered all-out efforts into the rescue work after a strong earthquake hit an autonomous county in southwest China's Yunnan Province on Sunday morning.

The earthquake, a magnitude of 6.4 on the Richter scale, has left three dead and injured more than 300 in the old downtown area of Hani and Yi Autonomous County of Ning'er, in Pu'er City.

In a statement issued by the Central Committee of Chinese Communist Party and the State Council, Hu Jintao, Premier Wen Jiabao and Vice-Premier Hui Liangyu asked provincial government officials in Yunnan "to mobilize all resources available to treat the injured and minimize the losses of lives and property of the public."

They also asked local authorities to closely monitor aftershocks and take good care of residents affected by the disaster.

The quake has forced the evacuation of 120,000 residents, according to a spokesman for the provincial civil affairs department.

A working group, involving officials from the Ministry of Civil Affairs and several other government agencies, arrived at the area Sunday night.