The search for survivors in the rubble of China's powerful earthquake grew bleak Sunday, with rescuers in some areas no longer listening for trapped victims.

There were a few tales of rescues even six days after the magnitude 7.9 quake in central China. But the focus of efforts in the disaster zone appeared to shift to clearing corpses from shattered buildings as the number of confirmed dead rose to 32,477.

Another 220,109 people suffered injuries, the official Xinhua News Agency reported. The government has said it expects the final death toll will surpass 50,000.

Click here to view video.

• Click here to view photos.

People ran into the streets as a strong aftershock — measured by the U.S. Geological Survey at magnitude 5.7 — shook the area early Sunday for 45 seconds.

Few hopeful relatives were seen in Beichuan, near the quake's epicenter, where several dozen corpses in blue body bags lay in a street, with soldiers regularly finding more dead in the wreckage. Rescue workers in the city sprinkled lime on the bodies and sprayed disinfectant nearby.

Wu Hai, a rescue team leader who came from neighboring Yunnan province, said bodies were in the middle stages of decomposition and "many of the limbs are broken off."

"There are definitely many more here. Locals here said several thousands have been buried here," he said.

A Malaysian rescue team in the town of Muyu, further north, sifted slowly and methodically through the wreckage, using giant cutters to split steel girders. However, they had apparently abandoned earlier efforts to tap on the debris in hopes that survivors would hear and respond.

Dozens of students were buried in new graves dotting a green hillside overlooking the rubble, the small mounds of dirt failing to block the pungent smell of decay wafting from the ground. Most graves were unmarked, though several had wooden markers with names scribbled on them.

Zhou Bencen, 36, said he raced to the town's middle school after the earthquake and found it had collapsed. Family members who arrived earlier had dug out the body of his 13-year-old daughter, Zhou Xiao, who was crushed on the first floor.

Zhou cradled his wife in his arms, holding her hand and stroking her back while she sobbed hysterically. "Oh God, oh God, why is life so bitter?" Liao Jinju wailed, over and over. The couple's 9-year-old son survived.

Experts say buried earthquake survivors can live a week or more, depending on factors including the temperature and whether they have water to drink — but that survival prospects diminish rapidly after the first 24 hours.

A "slightly bruised" man was pulled out alive from a collapsed hospital Sunday after being trapped for 139 hours, Xinhua reported.

The World Health Organization said conditions for homeless survivors were ripe for outbreaks of disease and called for quick action to supply clean water and proper hygiene facilities.

"Ensuring supply of food and safe drinking water and trying to restore good sanitation are critical because these are basic transmission routes for communicable diseases," said Hans Troedsson, WHO's representative to China.

Chinese health officials have not reported any disaster-related outbreaks so far.

Meanwhile, flood threats from rivers blocked by landslides from the quake appeared to have eased after three waterways near the epicenter overflowed with no problems, Xinhua said. County officials diverted released water as a precaution.

The quake damaged some water projects, such as reservoirs and hydroelectric stations, but no reservoirs had burst, Liu Ning, engineer in chief with the Ministry of Water Resources, told Xinhua.

Worries about possible flooding had sent thousands of people fleeing the day before.

Nuclear facilities jolted by the quake were confirmed Sunday as safe, said a man at the Ministry of Environmental Protection's Nuclear Safety Department who only gave his surname, Li.

China has a research reactor, two nuclear fuel production sites and two atomic weapons sites in Sichuan province, the French nuclear watchdog has said, all located 40-90 miles (60-145 kilometers) from the epicenter.

Chinese President Hu Jintao has urged rescue teams to reach remote villages battered by the earthquake where the level of damage remained unknown, according to Xinhua.

That was reinforced by a group of about 15 people who surrounded an Associated Press reporter at a gasoline station in Mianyang city Sunday, appealing for help for their village, Xiushui.

"The government is doing nothing to help us," said one man, who identified himself only by his surname, Chen. "If I gave you my complete name the government would track me down."

Chen did not say how many people lived there. He handed over a note which said it had been signed "by the people of Xiushui," and read, "Please go to our village of Xiushui to cover the situation. The government is doing nothing to help us get water or housing."

More international aid was arriving, with two U.S. Air Force cargo plane loaded with tents, lanterns and 15,000 meals landing Sunday in the Sichuan provincial capital of Chengdu.

"The current suffering of the people of China as a result of this terrible tragedy is in the thoughts and prayers of the American people," said Brig. Gen. Charles Hooper, defense attache at the U.S. Embassy in Beijing, who accompanied the shipment.

Most of the American supplies were to be rushed to hard-hit Beichuan, said Sr. Capt. Guan Youfei of the Chinese Defense Ministry's foreign affairs office.

A 24-hour online memorial to the victims sponsored by top Chinese Web sites was launched Sunday at 2:28 p.m., exactly six days after the earthquake, with forums for people to post messages of sympathy and virtual wreaths for the dead.