The quake hit the province's Tonghai county at 01:44 a.m. on Monday [17:44 GMT on Sunday], the CGTN broadcaster reported, citing the China Earthquake Networks Center (CENC).
Those wounded had been hospitalized and were in stable condition, the outlet added.
The authorities are reportedly conducting a rescue operation in the area.
Previous August, a powerful earthquake struck the Ngawa Tibetan and Qiang Autonomous Prefecture. It hit an area close to the Jiuzhaigou nature reserve, a tourist destination.Another powerful quake was registered shortly after in the same province.