At least 300 people were killed Wednesday and an additional 8,000 injured after a series of strong earthquakes in China's western Qinghai province toppled buildings and knocked out telecommunications, Chinese media say.

The China Earthquake Administration said a magnitude-7.1 tremor hit a southern area of the province near its boundary with Tibet, while the United States Geological Survey reported that the magnitude was 6.9 and that it was followed by two quakes in the same region.

The temblor struck at 7:50 a.m. local time and caused houses to collapse, covering people in rubble. The Chinese news agency Xinhua said at least 67 died, while others were still buried in the debris.

The main quake sent residents fleeing as it flattened houses made of mud and wood, said Karsum Nyima, a local TV news producer, speaking by phone with broadcaster CCTV.

'Terrible earthquake'

"In a flash, the houses went down. It was a terrible earthquake," he said. "Everybody is out on the streets, standing in front of their houses, trying to find their family members." He added that school buildings had not collapsed but that students had been removed to outdoor playgrounds.

The quake hit the county of Yushu, a Tibetan area in Qinghai about 2,000 kilometres west of Beijing, Xinhua said. A local government website puts the county's 2005 population at 89,300, a community of mostly herders and farmers.

In the town of Jiegu, near the epicentre of the first tremor, more than 85 per cent of the houses collapsed, Xinhua quoted a local official saying.

State television showed footage of paramilitary police using shovels to dig around a house with a collapsed wooden roof. A local military official, Shi Huajie, told state broadcaster CCTV that rescuers were working with limited equipment.

"The difficulty we face is that we don't have any excavators. Many of the people have been buried and our soldiers are trying to pull them out with human labour," Shi said. "It is very difficult to save people with our bare hands."

Roads badly damaged

Wu Yong, a local military chief, said medical workers were urgently needed but that roads leading to the airport had been badly damaged by the quake, creating difficulties for people and supplies to be flown in.

Telecommunications lines were temporarily knocked out by the seismic activity, and it was not immediately known whether the Qinghai-Tibet rail line, about 200 km away, had been damaged.

Ten minutes after the main tremor, the area was hit by a magnitude-5.3 quake, which was followed after two minutes by a temblor measuring 5.2, according to the U.S. Geological Survey.

In 2008, a magnitude-7.9 quake in China's Sichuan province left almost 90,000 people dead or missing.