At least 66 people were killed in a magnitude-6.8 earthquake that jolted Luding County, southwest China's Sichuan Province, local authorities said at a press conference on Tuesday afternoon.

Thirty-eight people were killed in Ganzi Tibetan Autonomous Prefecture, and the other 28 died in Shimian County of Ya'an City.

As of 7 a.m. Tuesday, 12 people were missing and 170 were found injured in Ganzi, including 56 seriously injured. A total of 78 people were injured in Shimian County as of 5:50 a.m. Tuesday.

The earthquake struck Luding County at 12:52 p.m. Monday (Beijing Time), according to the China Earthquake Networks Center.

Sichuan has activated the highest level of emergency response for the earthquake.

The Red Cross Society of China initiated a Level-III emergency response following the earthquake, with the first batch of relief materials consisting of 320 tents, 2,200 relief packages, 1,200 quilts and 300 folding beds dispatched to the affected area.

Local authorities are making all-out efforts to rescue the injured, speed up the opening of rescue channels and the repair of infrastructure in affected areas, prevent secondary disasters, and minimize casualties and losses.

As of noon Tuesday, the Department of Natural Resources of Sichuan Province has allocated 448 people, 111 vehicles and drones, as well as 146 sets of other equipment to participate in a secondary geological disaster emergency investigation, which has checked 501 hidden danger points and 15 new hidden danger points, CCTV News reported.  

At present, 11,252 people under threat have been evacuated, and no casualties have been reported due to secondary geological disasters in and around the quake-hit area, according to CCTV News. 

Mountainous Sichuan is prone to earthquakes. The 2008 Wenchuan earthquake left more than 80,000 people dead or missing.

(With input from Xinhua)