At least 8,700 people are dead and thousands more injured after a massiveearthquake rocked southwest China on Monday afternoon.

The quake, measuring 7.8 on the Richter scale, was the worst to strike China since the Tangshan earthquake in 1976, which claimed 242,000 lives.

The violent quake jolted Wenchuan County, 159 kilometers northwest of the provincial capital Chengdu, at 2:28 p.m. Monday.

Member of the Standing Committee of the Political Bureau of the Communist Party of China Central Committee and Chinese Pemier Wen Jiabao (C) arranges relief work of the earthquake during his flight for the disaster area on May 12, 2008. Premier Wen flew into southwest China's Sichuan Province on Monday afternoon and left straight for the quake-hit county of Wenchuan, 159 kilometers from the provincial capital of Chengdu, to oversee rescue work there.

Local residents sleep on the streets after an earthquake in Mianyang, Sichuan province May 12, 2008.

A spokesman with China Seismological Bureau (CSB) said the intense quake was felt in at least 16 provinces, municipalities and autonomous regions, including Beijing, Shanghai and Tibet.

The shocks, which were even felt in the Thai capital of Bangkok, 1,800 kilometers from the epicenter, leveled buildings, cut transport and electricity supplies, and caused flights to and from the affected areas to be canceled or postponed.

Chinese Premier Wen Jiabao, who arrived near the quake center Monday afternoon by plane, said the quake was a "major disaster" and called for calm and courage.

GREAT LOSS Officials in Sichuan said at least 8,533 people were dead in the province as of 10 p.m. Monday. In Beichuan, another county hard hit by the quake, the number of people dead is estimated at 5,000, and up to 10,000 people are injured.

GOVERNMENT RESPONSE President Hu Jintao called on government departments involved in disaster relief work to organize immediate first aid for the people and to ensure public safety. Premier Wen Jiabao arrived in Chengdu late Monday and was in Dujiangyan to direct rescue work.

RESCUE UNDERWAY Huaxi Hospital, the largest hospital in Chengdu, has taken in 106 patients after the quake. The hospital set up an emergency rescue center, and kept all of its medical staff available on duty.

EXPERT ANALYSIS More than 300 aftershocks were registered after the quake, and a Chinese seismologist warned residents in earthquake-affected areas in southwest China of more tremors, which could be just as devastating.