CHONGQING, China — CHONGQING, China -- A powerful earthquake rocked China from mountains to coast yesterday afternoon, knocking down schools, homes and factories, and killing nearly 10,000 people.
The quake was centered in western China's Sichuan province but was so powerful that it was felt over thousands of miles from Beijing to Bangkok, Thailand. It forced the evacuation of China's tallest building, Shanghai's Jinmao Tower, and sent high-rise workers around the country scurrying for safety.
China instituted tight controls on information, setting up checkpoints to bar Chinese and foreign correspondents from severely affected areas.
The quake was first reported as magnitude 7.8. The U.S. Geological Survey now says it was 7.9.
Many of the dead were reported to be children. The New China News Agency said that at least eight schools had collapsed; one of them was a high school where, as of last night, workers were trying to rescue 900 teenagers trapped under the rubble.
The news agency said 8,533 people were killed in Sichuan.
The earthquake was recorded at 2:28 p.m. with an epicenter in Wenchuan county, about 60 miles to the northwest of Chengdu, Sichuan's capital. The area is best known for the Wolong Nature Reserve, the largest breeding ground of captive pandas. The area has a large Tibetan population and has been the scene of anti-Chinese protests.
Sichuan officials said that in Beichuan county, 80 percent of the buildings were reported to have collapsed. Deaths also were reported in Gansu and Yunnan provinces and in the city of Chongqing, hundreds of miles from the epicenter. At least four of the dead there were schoolchildren.
Liu Zhao, 22, a student, said he was home in a third-floor apartment in a high-rise building in central Chongqing when the quake struck.
"Lots of people were running; the whole community was terrified," Liu said. "People were very scared, you could tell the way people were acting. All communications were cut or overloaded almost immediately with everyone busy trying to make calls."
Zhao Cunfu, a teacher at the Lirang Village Elementary School in Chongqing, said by telephone that he was sitting in his office when he suddenly felt dizzy. Stumbling into the hallway, he realized what was happening and tried to escort a crowd of first-graders out of the building.
"The children panicked," Zhao said. "They were pushing one another. They were very small. It was easy for them to get hurt."
In Chengdu, a city of 11 million, witnesses described a panic as the quake hit.
"Cars were bouncing along the street. Everyone came rushing out of their buildings," Chris Fay, a British bar owner, said in a telephone interview over the howl of sirens in the background.
"It lasted a long time, maybe four or five minutes," said Daisy Cang, a bookstore employee in Chengdu, who was alerted to the quake when the beer cans in her refrigerator toppled over.
Fearful of aftershocks, residents poured into the streets. Chinese state television showed footage of office workers with their laptops at an outdoor cafe, while others lounged around flower beds, appearing to enjoy a rare break.
But the television showed none of the more gruesome scenes from the earthquake, and glimpses of the devastation came only from short items offered by the official news agencies.
It was reported that a chemical plant collapsed in Shifang, to the northeast of the epicenter, spilling 80 tons of toxic liquid ammonia. Hundreds of people were said to be trapped in the rubble.
In Dujiangyan City, where 900 students were trapped inside the remains of their junior high school, the Xinhua news agency described the parents standing around in horror as construction cranes picked through the rubble looking for survivors.
"Some had jumped out of the window and a few others ran down the stairs that did not collapse," Gao Shangyuan, a volunteer rescue worker, told Xinhua.
It has been difficult to get information from the epicenter of the earthquake because mountain roads were damaged and telephone lines severed. Deng Changwen, vice director of the Sichuan bureau of telecommunications, told Chinese television there had been a "total failure" of the communications network.
Premier Wen Jiabao, a geologist by training, called the quake "a major geological disaster" and traveled to the disaster area to oversee rescue and relief operations.
"Hang on a bit longer; the troops are rescuing you," Wen shouted to people buried in the Traditional Medicine Hospital in the city of Dujiangyan, on the road to Wenchuan, in comments broadcast by CCTV.
"As long as there was a slightest hope, we should make our effort a hundred times, and we will never relax," he said outside the collapsed school in Juyuan.
The quake was the deadliest since one in 1976 in the city of Tangshan that killed 240,000 - although some reports say as many as 655,000 perished - the most devastating in modern history. A 1933 earthquake near where yesterday's struck killed at least 9,000.
Yesterday, about 5,000 troops and a 180-member team from the national earthquake center were dispatched to the disaster area.
A large number of troops from the Peoples' Armed Police, a paramilitary force, are already in place, deployed in the area as a result of anti-Chinese protests in March.
The epicenter was in part of what is called the Tibetan-Qiang Autonomous Prefecture. The small town of Aba within the prefecture in particular has been a hotbed of unrest, with Buddhist monks marching against Chinese rule since mid-March.
Mark Magnier and Barbara Demick write for the Los Angeles Times. The Associated Press contributed to this article.