CHONGQING, China - A huge earthquake rocked southwest China killing more than 8,700 people Monday, flattening schools, factories and homes and rattling cities across a swathe of southeast Asia. The quake, with a magnitude of 7.8, struck close to densely populated areas of Sichuan province in what Premier Wen Jiabao called a 'major disaster.' China's state-run Xinhua news agency reported 8,533 confirmed dead in that province alone, but the overall toll looked certain to rise with scores killed in neighbouring regions and hundreds buried under debris. Buildings swayed in Beijing and Shanghai, while the quake was felt in Hong Kong, Vietnam and in the Thai capital Bangkok, 1,800 kilometres from the epicentre. "I heard the vents ruffling and then started to feel the building shake and a couple of bits of the ceiling fell," Richard Morgan-Sanjurjo, a 30-year-old business consultant in Chengdu, provincial capital of Sichuan, told AFP. "I ran so fast. I thought the building was going to come down on my head," he said. Xinhua quoted disaster relief officials saying up to 5,000 people died in one Sichuan district, Beichuan, where 80 percent of buildings collapsed. "Facing disaster, the most important thing is calm, confidence, courage and strong leadership," Wen told China's CCTV television on a plane to Chengdu to oversee rescue operations. Worryingly, there was little news out of Wenchuan county, the mountainous region at the epicentre, more than 12 hours after disaster struck, although Xinhua reported at least 30 dead there. All lines of communication were cut with the county, which has a population of 112,000 and is home to the Wolong Nature Reserve, China's leading research and breeding base for endangered giant pandas. "We are doing everything we can but the roads are blanketed with rocks and boulders," Xinhua quoted Li Chongxi, a Communist Party official, as saying. The health ministry despatched emergency medical teams to Wenchuan and the Chinese Red Cross sent tents and quilts. The civil affairs and finance ministries allocated 200 million yuan (about 28.6 million dollars) for the relief effort. The death toll is the highest for a quake in China for three decades since 242,000 died in a 1976 quake that flattened the northern city of Tangshan. US President George W Bush expressed his condolences and said the United States "stands ready to help," and Japan said it was ready to provide as much relief aid as possible. Russia also offered help. The quake damaged two chemical plants in Shifeng, burying several hundred people and forcing the evacuation of more than 6,000 nearby, Xinhua said. Meanwhile, up to 900 students were buried under a collapsed high school in Dujiangyan, northwest of Chengdu. Rescuers recovered at least 50 bodies while those still trapped called out for help as frantic parents looked on. President Hu Jintao urged an 'all-out' effort to rescue victims and troops were ordered to help with disaster relief work. All trains to and from Chengdu were stopped, the city's airport was closed and planes diverted for engineers to assess the runways. Mobile phone and Internet communications were disrupted. An Olympic spokesman said none of the 31 venues for the Beijing Olympics in the capital and other host cities had been damaged. The quake's epicentre was about 93 kilometres from Chengdu, a city of more than 12 million people, and 260 kilometres from Chongqing and its 30 million. It struck shortly before 0630 GMT at a depth of just 10 kilometres, the US Geological Survey said. An official said the landmark Three Gorges Dam in Sichuan province had not been affected. However, buildings shook in Beijing and Shanghai, residents reported, with many people evacuating tower blocks and rushing onto the streets. The quake was felt in the Taiwanese capital Taipei, where towers swayed for half a minute, and in the southern Chinese territory of Hong Kong. In Hanoi, residents said some high buildings shook for around five minutes but there were no reports of damage.