State media reports indicated that the number of dead was likely to soar, with Xinhua news agency saying 10,000 people were buried in the Mianzhu area of Sichuan province and that rescue troops had arrived for the first time at Wenchuan county, the epicentre of the quake.
Death tolls in different areas are official estimates, given lack of access to worst-hit areas and inability to make accurate body counts under collapsed buildings.
Premier Wen Jiabao, visiting Sichuan, ordered troops to clear roads to Wenchuan, a hilly area about 100 km (62 miles) from the provincial capital Chengdu.
Damage from Monday's 7.9 magnitude quake left the area, about 1,600 km southwest of Beijing, completely cut off.
But rain and thick clouds over a province famous for its giant panda reserves meant that military helicopters dispatched to the area could not yet land. Parachutists belonging to the People's Liberation Army cancelled a rescue drop due to heavy storms, Xinhua said.
State television showed highways buckled and caved in from the quake and massive rockslides lining the roads.
In Dujiangyan - about midway between Chengdu and the epicentre - there was devastation, with buildings reduced to rubble and bodies in the streets, some only partially covered.
Troops and ambulances thronged the streets, and military trucks able to do heavy lifting had arrived. But many residents simply stood beside their wrecked homes, cradling possessions in their arms, and many huddled in relief tents under heavy rain.
"At least 60 or 70 old people lived there, as well as children," said a hospital worker surnamed Huo, gesturing to a building in ruins. Mattresses and household objects could be seen poking through the rubble.
"How could they survive that?" she asked.
Rescuers had worked frantically through the night, pulling bodies from homes, schools, factories and hospitals demolished by the quake, which rolled from Sichuan across much of China.
In the same city, about 900 teenagers were buried under a collapsed three-storey school building. Premier Wen bowed three times in grief before some of the first 50 bodies pulled out, Xinhua reported.
"Not one minute can be wasted," said Wen, a trained geologist. "One minute, one second could mean a child's life."
Frantic relatives tried to push past a line of soldiers surrounding the school, desperate for news of their children.
