Sweating away amid the stench of death with no food for more than 20 hours, 19-year-old Zhu Yuantong said he doesn't care: he's saving lives.

Zhu owns a pet store in Mianyang City, Sichuan. After Monday's earthquake, he left his business and volunteered to help in the rescue work in Beichuan County, near the epicenter of the quake. About 80 percent of the buildings are destroyed, and more than 5,000 people are believed dead.

Liu Deyun, 56, is carried out by soldiers after being buried for 100 hours in a collapsed building at a chemical factory in the earthquake-hit Yinghua town of Deyang, Sichuan province, May 16, 2008. [Agencies]

Four days after the tremor, volunteers, police, medics and soldiers and fire-fighters are moving through the rugged mountains, venturing across suspension bridges and trekking through rivers to save lives.

"Beichuan is one of the areas worst hit by the earthquake. When I came, I was prepared," said Zhu, who arrived on Thursday.

After hours of work in the debris, Zhu's clothes are tattered, his ankle and legs lacerated, and some wounds appeared to be festering. But with calm and composure, Zhu successfully led the rescue of a buried nurse.

"About 5 a.m., I met a man in yellow shirt. He was running and gasping, 'There's a person at a clinic buried but alive, you need to go and rescue her,'" Zhu recalled.

"As we rushed there, more volunteers joined us. They were from my city, Chongqing and Shanghai."

Xinhua reporters joined the team and on their way saw people shouting the names of relatives, and wailing.

Volunteers carry a survivor from the ruins of a collapsed apartment block in the city of Beichuan, located around 150 km north of Chengdu, in Sichuan Province May 16, 2008. China struggled to bury its dead and help tens of thousands of injured and homeless on Friday when a powerful aftershock brought new havoc four days after an earthquake thought to have killed more than 50,000. [Agencies]

When the volunteers arrived at the clinic, a geologist surnamed Mei and his son were already there. They had first realized the nurse was alive.

"I heard a weak voice about 2 a.m. when I passed by, but without rescue equipment, we could only talk to her to keep her going," Mei said.

"Luckily she understood how to conserve her strength. We shouted and she responded by knocking on some pipes," he said.

The nurse was Duan Zhongying, 23, buried beneath the rubble of a five-storey building.

The volunteers called in about ten firefighters who were working nearby and at about 7 a.m., the rescue began.

"I THOUGHT SHE WAS DEAD"

During the rescue operation, a man was seen wandering among the debris. He burst into tears when he learnt the buried woman was his fiancee.

"I can't remember how many times I've come here since the tremor, and I almost lost hope," cried Li Bolan.

"We were planning to get married, and we've already had a new house built. My six-year-old nephew was buried in his kindergarten not far away, and my parents were also buried," he said.

Li lay on the debris and shouted to his fiancee, and during the eight-hour rescue, the rescuers all took turns to reassure the woman.

"You need to trust us -- we're not leaving until we get you out," shouted Liang Chun, one of the volunteers.

As they were prying away the cement slabs and steel bars, an after-shock struck around 9:57 a.m.

"Everybody calm, no one move." shouted Wang Shijun, a fire-fighter.

The rescuers supported each other and proceeded with the operation.

"There is a thick door, get the cutting equipment."

"Her arm is out. Get her some water."

One of the women volunteers stooped to give her a bottle of sugared water and helped to put straw into her mouth.

After spending 96 hours stuck between stairs, the nurse was finally freed. Tears and cheers followed.

"When someone is buried beneath us, we have no time to lose," said Zhu. "Nothing is more satisfying than saving lives."

"WHAT WE'RE HERE FOR"

After the 7.8-magnitude earthquake hit Sichuan, people from all walks of life have mobilized, and the volunteers are at the front line.

Some volunteers rummaged through the debris to retrieve packaged or canned foods for the hungry, some counseled the victims and their families, and others helped carry the injured and bodies. In the hills near Beichuan, a volunteer collapsed after rushing an injured person to an ambulance.

Xiao Li, a former woman soldier who helped to save the nurse, said, "I tumbled down a hill, my legs shake when I cross the suspension bridge, but that's what we're here for. I'm not so scared.

"There are braver people around. I was at a school the other day, and one of the girls was seriously injured, but she asked the soldiers to save her classmates first. I heard another girl singing to cheer up her friends with her under the debris," Li said.

"I will not leave until I am no longer needed," Li said.

After the rescue, the volunteers fanned out and began searching again.

Editor: Yan