Rescue workers have been trying to reach students of Juyuan Middle School
Almost 900 students are buried after an earthquake measuring 7.8 caused a building to collapse in south-western China, state media reports.
President Hu Jintao urged "all-out" efforts to rescue victims of the quake, which hit 92km (57 miles) from Chengdu, Sichuan's provincial capital.
Premier Wen Jiabao is travelling to the area and troops are being sent to help with disaster relief efforts.
Officials have confirmed 107 deaths in the area but the figure could rise.
Cries for help
There are harrowing reports from the scene of the collapse in Dujiangyan city - about 100km (60 miles) from the epicentre in Wenchuan county.
Teenagers buried beneath the rubble of the three-storey Juyuan Middle School building were struggling to break free, while others were crying out for help, state news agency Xinhua reported.
Parents were watching as cranes excavated the site. Villagers rushed to help with the rescue.
Two girls said they escaped because they had "run faster than others".
Earlier, four schoolchildren were reported to have died, and more than 100 others were injured, when primary school buildings collapsed in the Chongqing area near Sichuan province, Xinhua reports.
Another person is reported to have died when a water tower collapsed in the city of Mianyang, in Santai county.
A spokesman for Gansu province said 10 people were killed and 14 injured by collapsing buildings in Pingliang and Longnan.
Forty-four aftershocks have been reported since the quake, which was the strongest to hit Sichuan province in more than 30 years, Xinhua reports.
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Eyewitness Gilles Barbier: 'It was very scary'
Troops and helicopters have been sent to help with relief work.
The BBC's Quentin Somerville says the Chinese army has a good record of mobilising and getting people to safety.
State television said the quake had not caused major damage to Chengdu, which has a population of more than 10 million people, or to the nearby Three Gorges Dam.
RECENT CHINA QUAKES
March, 2008: 7.2 quake in Xinjiang - damage limited
February 2003: 6.8 quake in Xinjiang - at least 94 dead, 200 hurt
January 1998: 6.2 quake in rural Hebei - at least 47 dead, 2,000 hurt
January 1997: 6.4 quake in Xinjiang - 50 dead, 40 hurt
In Chengdu, residents streamed on to the streets, cracks were reported in some buildings and water pipes burst.
"Some building are cracked, but nothing major, from what we can see in the area near our hotel," Gilles Barbier in Chengdu told the BBC News website.
"The quake was really strong, continuous. Two aftershocks could be felt."
Workers in Beijing - about 930 miles from Chengdu - said buildings shook for about two minutes and many were evacuated.
In the city's financial district, people poured out of buildings, but there were no visible signs of damage.
Tremors were also felt as far afield as the Thai capital, Bangkok, and Hanoi in Vietnam.
Panic
One student fainted as schools were evacuated across Sichuan province
Bobby Silby in Zhengzhou in Henan province said he was having lunch in a restaurant when he felt the tremors.
"It felt like the floor was moving all around me, everyone started running outside in a panic," he told the BBC news website. "The streets are still filled with people who haven't gone back into their buildings."
Telephone lines to the affected areas were jammed.
The area where Monday's earthquake struck lies on the eastern edge of the Tibetan plateau.
Wenchuan county is home to the Wolong Nature Reserve, China's leading research and breeding base for endangered giant pandas.
Earthquakes are common in China - in March a 7.2 magnitude quake struck in western Xinjiang province, though the damage was limited.
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