Rescuers were using shovels and their bare hands and working in freezing temperatures.
Hu Jintao, the Chinese president, called for an all-out effort to save as many people as possible, with more than 5,000 rescuers including soldiers sent to the disaster zone and the government saying it would provide more than $29m in aid.
While China's military is well-practiced in responding to disasters, the remote location is posing logistical difficulties.
Al Jazeera's Melissa Chan, reporting from Yushu town on Thursday, said it is a very long drive through a mountainous region, with landslides partially blocking the road, to reach the quake zone.
"One of the challenges is going to be the altitude … getting to this area can be quite tough and it is taxing on people who are not used to the high elevation," she said.
The airport in provincial capital Xining, the nearest big city 860km away, was filled with Chinese troops, firefighters and rescue teams leading dozens of sniffer dogs early on Thursday.
They were whisked on to waiting buses for the difficult drive to the quake zone, but that journey takes 12 hours under the best of conditions.
Crews set up emergency generators to restore operations at Yushu's airport, and by late afternoon on Wednesday the first of six flights had landed carrying rescue workers and equipment.
The small Yushu airport also has no refuelling supplies, so relief flights were carrying extra jet fuel, reducing their capacity for hauling emergency supplies, state media reported.
"The situation here is difficult. Most of the buildings have collapsed. A lot of people are seriously injured," said Pu Wu, a director of the Jinba Project, which provides healthcare training for Tibetan communities.
"We are scared. We are all camping outside and waiting for more tents to come."
In the cold
Still, the rescue effort appeared to be very well-organised, our correspondent said, with many of the convoys already in town bearing signs saying that they had also been at the Sichuan quake in 2008.
|Rescuers working with limited equipment have pulled hundreds alive from the rubble [Reuters]
In Yushu, many buildings had collapsed and people were just standing around in a daze, our correspondent said.
Survivors said a lot of rescue work had taken place in the first 24 hours, with people moving from one pile of rubble to another, looking for those trapped or buried alive, our correspondent said.
Many survivors had spent the night outdoors as temperatures dropped below freezing, wrapping themselves in thick blankets and lying on thin pads on the ground with cardboard boxes serving as makeshift pillows.
Others slept in quake-damaged cars, covering exposed areas with sheets of plastic, state-run television footage showed.
The quake, measured at magnitude 7.1 by the China Earthquake Administration and at 6.9 by the US Geological Survey (USGS), struck the Tibetan plateau at 7:49am on Wednesday.
It was centred in the mountains that divide Qinghai province from the Tibet Autonomous Region, 380km south-southeast of the city of Golmud.
Quakes are commonplace in the region, but usually cause little loss of life due to the spread of population.
|Officials said 15,000 houses collapsed and 100,000 people need to be relocated [Reuters]
But Wednesday's quake flattened earth-and-wood houses and felled sturdier concrete buildings across Yushu and sent survivors, many bleeding from their wounds, flooding into the streets of Jiegu.
State television showed block after devastated block of toppled mud and wood homes. Local officials said nearly nine out of 10 buildings had been destroyed in Jiegu.
Several schools collapsed, with the state news agency saying at least 56 students had died.
Worst hit was the Yushu Vocational School, where 22 mostly female students were killed, Xinhua cited a local education official as saying.
The destruction of schools is an eerie echo of the massive magnitude-7.9 quake that hit neighbouring Sichuan province two years ago, leaving around 80,000 people dead or missing.
Thousands of students among the dead were killed when their schools collapsed.
Poor design, shoddy construction and the lax enforcement of building codes were found to be rampant in that disaster.