No casualties have been reported following a 6.9-magnitude earthquake that hit Nyingchi in southwest China's Tibet Autonomous Region at 6:34 a.m. Saturday.

However, the quake caused power failure and building damages in a number of villages in the epicenter in Nyingchi City.

The epicenter was detected at 29.75 degrees north latitude and 95.02 degrees east longitude, according to the China Earthquake Networks Center.

The quake struck at a depth of about 10 km. Four minor aftershocks measuring between 5 magnitude and 3.1 magnitude were felt in the city's rural areas.

Basang Cering, Party chief in Zhaxigang Village of Lunang Township, told Xinhua that he could not stand still in his house when the quake struck. Six houses in his village were damaged by the jolt.

Sources with the regional power grid said the power grids of both Tibet and Nyingchi are operating normally, though it had launched an emergency response mechanism.

The China Seismological Bureau has launched a third-degree emergency response mechanism, holding a teleconference to monitor an investigation into the situation and sending experts to the quake-hit region.

The bureau observed that the highest seismic intensity of the quake affected an area of 500 square meters, which is sparsely populated.

The tremors triggered falling rocks, blocking a highway linking Nyingchi's city proper with Tangmai, one of the quake-hit townships. Armed police transport troops are clearing the road.

The Fire Department of the Ministry of Public Security said fire fighters from Nyingchi city are ready in Tangmai Township. Another team of rescuers will take helicopter to Gyalha village in the epicenter, after road to the village was blocked by rocks.

The Ministry of Transport has also dispatched staff to investigate the safety condition of bridges in the quake-hit area.

The Tibet subsidiaries of Chinese telecom providers China Mobile and China Tower said that their networks are operating normally. But the Tibet branch of China Telecom reported the disruption of an optical cable for broadband service in Pome and Zayul counties.