RESCUE
The China Earthquake Administration has also sent 60 rescuers and 30 medical workers to the quake-hit region.
The China Eastern Airlines has arranged two aircraft for transporting rescuers and relief supplies.
The Qinghai Provincial Department of Civil Affairs has allocated 5,000 tents to the region.
Meanwhile, the Ministry of Civil Affairs has allocated 5,000 tents, 50,000 cotton-padded clothes and 50,000 quilts to the region.
The Red Cross Society of China has dispatched a relief team to Yushu and allocated 100,000 yuan (14,706 U.S. dollars), 500 tents, 1,000 cotton-padded clothes and 1,000 quilts as relief supplies.
In addition, authorities in Beijing have donated 10 million yuan to Yushu and dispatched an 80-member medical team there. They also sent 10,000 tents, 20,000 beds and 100,000 quilts there.
Pupils of some primary schools were among the buried, but the number was unknown, said Shi Huajie, an army police officer in the rescue operation.
"We have to mainly rely on our hands to clear away the debris as we have no large excavating machines," he said. "We have no medical equipment, either."
Wu Yong, commander of the Yushu Military Area Command of the Chinese People's Liberation Army, said the death toll "may rise further as lots of houses collapsed."
"We are now putting up tents and transporting oxygen to prepare for treating the injured," he said.
"But roads leading to the airport have been damaged, hampering the rescue efforts," he said.
"In addition, frequent aftershocks and strong winds make the rescue operation more difficult," he added.
The quake struck the Yushu County in the Yushu prefecture at 7:49 a.m. with a depth of about 33 km. The epicenter is calculated to be 33.1 north and 96.7 east, the China Earthquake Networks Center reported.
At least 18 aftershocks have been reported so far, with the biggest being 6.3 magnitude about an hour and 36 minutes later.
"Aftershocks above 6 magnitude are still likely to happen in the coming several days," warned Liu Jie, of the China Earthquake Networks Center.
Earlier at 5:39 a.m. Wednesday, a 4.7-magnitude jolted the county with a depth of about 6 km, the center reported.
Yushu is a quake-prone region.
An 8.0-magnitude quake centered in Wenchuan County in Sichuan on May 12, 2008 left 87,000 people dead or missing.
In terms of the intensity and scope of destruction, the Wenchuan quake is believed to have surpassed the 7.8-magnitude quake in 1976 in Tangshan, northern Hebei Province, which claimed more than 240,000 lives.