The casualties were reported in the county of Ninglang in Yunnan province, a spokesman with the Yunnan Provincial Seismological Bureau said.
The quake was strongly felt in the county, and the bureau has dispatched a team to the area to investigate losses, he said.
Local authorities have sent 300 tents, 500 quilts and 500 cotton-padded clothes to the county, said Bai Yong, director of the Disaster Relief Section of the Yunnan Provincial Civil Affairs Department.
The quake struck the border of Yunnan and Sichuan provinces at 3:59 pm (local time) today, according to the China Earthquake Networks Centre.
Telecommunication networks in the county's Yongning township were cut by the quake.
A spokesman with the Yanyuan county government told Xinhua that the quake was not strongly felt in the county seat, but many houses in the countryside collapsed.
The epicentre, was located at the border area between Ninglang and Yanyuan county ofSichuan at 27.7 degrees north latitude and 100.7 degrees east longitude.