BEIJING — A powerful earthquake rocked a region of southwest China Monday, killing nearly 10,000 people, burying schoolchildren in collapsed classrooms and rattling high-rise buildings across much of East Asia. The earthquake, measuring 7.9 on the Richter scale, struck in the early afternoon in a rugged region of densely populated Sichuan province, where bamboo forests provide a home to China's endangered giant pandas. In the hours after the earthquake struck at 2:28 p.m., rescuers rushed to pull survivors out of collapsed buildings and schools, and the official Xinhua news agency steadily increased the death toll, arriving at "nearly 10,000" by early Tuesday morning. The U.S. Geological Survey said the quake struck 55 miles west-northwest of the Sichuan provincial capital of Chengdu and was centered 18 miles below the surface. The quake was felt as far away as Bangkok, Thailand, in the Vietnamese capital of Hanoi, in Pakistan and on the island of Taiwan. Office workers wobbled out of swaying high-rises in Beijing, Shanghai and Hong Kong, dizzy from the motion. President Hu Jintao ordered an “all-out” effort to rescue victims, and Premier Wen Jiabao said China would "definitely overcome this major disaster."
"The most important thing is calm, confidence, courage and strong leadership," Wen told a state television reporter aboard a jetliner taking him to the earthquake zone.
Disaster relief officials told Xinhua that 3,000 to 5,000 people are believed to have died in one Sichuan area alone, Beichuan County, where 80 percent of the buildings collapsed. Another 10,000 people were injured in the county. Boulders the size of houses blocked roads, and the old section of Beichuan town was reduced to rubble, it added.
Also severely hit was Wenchuan County, northwest of Chengdu. In one city, Dujiangyan, Xinhua said up to 900 students were feared buried in the collapsed three-story Juyuan Middle School.
It said that students struggled "to break loose from underneath the ruins while others were crying out for help." News photos showed twisted mounds of concrete and crushed bodies. Rescuers deployed five cranes to help clear away rubble.
A rupture at a chemical plant in Shifang City, northeast of the epicenter, spilled 70 tons of toxic liquid ammonia, Xinhua said, and the city reported 600 deaths, including 81 students, and 2,300 people remained missing.
China's Ministry of Civil Affairs said fatalities also occurred in Yunnan and Gansu provinces, as well as in the sprawling city of Chongqing on the Yangtze River.
Xinhua quoted an official saying that the mammoth Three Gorges Dam in Sichuan province hadn't been affected. The 380-mile reservoir behind the dam has been prone to quake-triggered landslides.
In Chengdu, the Sichuan capital of 11 million residents, the strong jolt cracked walls, toppled glasses off tables, broke water mains and downed power lines. Thousands of residents milled in city streets, fearful as dozens of aftershocks shook the province. Authorities suspended rail service and diverted incoming flights from the city's airport.
"Power poles and flagpoles were shaking. Buildings shook, and I could hear windows rattle," said Shen Jianfeng, a teacher at the Southwest University for Nationalities.
Shen said mobile phone service had been interrupted, leaving him unable to contact his wife and mother. "I don't know whether they are OK," he said.
Residents in Mianyang, a city north of Chengdu, sent mobile phone text messages saying several buildings had collapsed during the quake. Xinhua said "rows of houses" were toppled in Dujiangyan.
Students died in schools in Liangping County, near the city of Chongqing, and in Dujiangyan, Xinhua said. Another person was killed when a water tower collapsed in Mianyang, it added. State television said 47 of the fatalities were in Chengdu.
Buildings swayed in Beijing and Shanghai, prompting many office workers to rush out into the streets. In Beijing's China World office building, paintings fell from walls on high floors.
Office workers were evacuated from mainland China's tallest building, the 1,380-foot-tall Jinmao Tower in Shanghai, as well as other high-rise buildings along Hongqiao and Nanjing roads.
China's deadliest earthquake in the past century hit the eastern city of Tangshan in 1976, killing 242,000 people. That quake, also magnitude 7.8, knocked down 90 percent of the city's buildings, devastating a local population of 1 million people.
(McClatchy Newspapers special correspondent Fan Di contributed.)