As of 9.30 a.m., the quake has also left 175 others injured, the official told Xinhua news agency.
The quake jolted Jiuzhaigou county, a popular tourist destination, at 9.19 p.m. at a depth of 20 km.
At least five deaths reported immediately after the quake were those of the visitors to Jiuzhaigou, the publicity department of the Aba Tibetan and Qiang Autonomous Prefecture that administers the county, said.
Sangey, a worker at the popular Jiuzhaigou tourist site, told Xinhua on telephone that some houses in the scenic area collapsed or cracked in wake of the powerful quake. Authorities were evacuating the residents.
There were reported house collapses in towns like Heihe, Shuanghe and Anle, the department said.
Li Changyong, head of the Jiuzhaigou county health and family planning bureau, said the quake was strongly felt in the county seat, 35 km from the epicentre and many residents rushed out of buildings.