A powerful earthquake struck today close to densely populated areas of southwestern China, flattening schools and homes and killing more than 100 people, according to early estimates.
Nearly 900 students were feared buried and four killed today when a high school building collapsed in southwestern China, state-run Xinhua news agency said.
The quake, with a magnitude of 7.8 on the Richter scale, was felt in cities across a swathe of South-East Asia including the Thai capital Bangkok, more than 1,800 kilometres from the epicentre in Sichuan province.
The collapse occurred in the city of Dujiangyan in Sichuan province near the quake's epicentre, said the report.
At least four children were confirmed dead there, Xinhua said, and quoted a local official saying "rows of houses" had also been demolished.
Another four children died and more than 100 were injured when two primary schools crumbled in the sprawling metropolis of Chongqing.
The civil affairs ministry, cited by Xinhua, said that as at 6pm (2000 AEST), nearly four hours after the quake struck, 107 people had been confirmed dead and 34 injured in Sichuan and neighbouring Gansu and Yunnan provinces.
"Facing disaster the most important thing is calm, confidence, courage and strong leadership," Wen told China's CCTV television on a flight to the heart of the quake-hit zone.
"We will definitely overcome this major disaster."
Chinese Premier Wen Jiabao called it a "major disaster" and urged calm.
President Hu Jintao urged an "all-out" effort to rescue victims. Military troops were ordered to help with the disaster relief work.
The international airport at Chengdu, the capital of Sichuan province, was closed and air travel disrupted elsewhere.
The quake struck 93 kilometres from Chengdu, a city of more than 12 million people, and some 260 kilometres from Chongqing and its 30 million.
Buildings shook in Beijing and Shanghai, residents reported, with many people evacuating tower blocks and rushing onto the street. There were no immediate reports of damage there.
Tremors were also felt in Bangkok, Hong Kong, Hanoi and Taipei, residents there said.
Both the Chinese seismological bureau and the US Geological Survey (USGS), which use different scales, measured it at 7.8.
Two residents near downtown Chengdu whom AFP contacted by phone said they felt a violent shaking that threw glassware to the floor and toppled street lights.
In Hanoi, residents said some high buildings shook for around five minutes but there were no reports of damage.