A major earthquake measuring 7.8 on the Richter scale jolted Wenchuan County in southwest China's Sichuan Province at 2:28 p.m. on Monday, the State Seismological Bureau (SSB) said. The epicenter was 90-kilometers away from the provincial capital, Chengdu. The hardest hit county, Wenchuan, with a population of 111,800, lies in southeast part of the Tibetan-Qiang Autonomous Prefecture of Aba, 146 km to the northwest of Chengdu, provincial capital of Sichuan has a large ethnic Tibetan population. Wenchuan County is also home to the Wolong Nature Reserve, China's leading research and breeding base for endangered giant pandas. Some 900 students were feared buried by a mudslide caused by the quake when a Sichuan high school building collapsed, Xinhua news agency reported. In a separate incident, four students were killed and at least 100 were injured when two schools collapsed in Liangping county of Chongqing municipality, adjacent to Sichuan, state-run Xinhua said. Yahoo: Death toll in China earthquake rises to 7,600. The Guardian: China earthquake kills thousands.