A major earthquake measuring 7.8 on the Richter scale jolted Wenchuan County of southwest China's Sichuan Province at 2:28 p.m. Monday, the State Seismological Bureau said, revising a previous figure of 7.6.

The epicenter of the quake was located 31.0 degrees north latitude and 103.4 degrees east longitude, the bureau said.

With a population of 111,800, Wenchuan lies in southeast part of the Tibetan-Qiang Autonomous Prefecture of Aba, 146 km to the northwest of Chengdu, provincial capital of Sichuan.

An earthquake measuring 3.9 on the Richter scale jolted Tongzhou District in east Beijing at 2:35 p.m. Monday. The quake's epicenter was located 39.8 north latitude and 116.8 east longitude, according to the State Seismological Bureau.

Xinhua reporters in many other parts of China also reported tremors.

A retiree in Leshan, a city of the southwestern Sichuan Province, said via telephone that a wall in her garden collapsed, while a repairman in Chongqing saw the ceiling of his factory shamble and alarmed the staff, who soon left the building.

In Shanghai, people were evacuated from office buildings in Hongqiao and Nanjing Road.

Mobile phones in Chengdu and Chongqing could not be reached for a while on Monday afternoon.

No casualty was reported yet.

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