About 400 people have died and 8,000 others were injured after a 7.1-magnitude earthquake hit northwest China's Qinghai Province early on Wednesday, a local official said.

President Hu Jintao and Premier Wen Jiabao have ordered local authorities to go all out to save the disaster-stricken people.

Vice Premier Hui Liangyu has rushed to the quake-hit region.

Many people are still buried under the debris of collapsed houses in the Gyegu Town near the epicenter in the Tibetan Autonomous Prefecture of Yushu in southern Qinghai, said Huang Limin, deputy secretary-general of the prefecture government.

The strong quake and a string of aftershocks, with the biggest one being 6.3 magnitude, have toppled houses, temples, gas stations and electric poles, triggered landslides, damaged roads, cut power supplies and disrupted telecommunications. A reservoir was also cracked, where workers are trying to prevent the outflow of water.

Gyegu, also known as Jiegu, is the seat of the Yushu prefecture government. The town has a population of about 100,000, including permanent residents and migrant people.

About 700 soldiers are now struggling to clear away the rubble and rescue the buried people, a spokesman with the Qinghai Provincial Emergency Office said.

More than 5,000 additional rescuers, including soldiers and medical workers, have been dispatched to the quake-hit region, according to a news conference held by the Qinghai provincial government.