A young boy has told how he was buried alive for five days after the Nepal earthquake that killed more than 6,000 people.

Pempa Tamang, 15, said he listened to bulldozers clearing mountains of debris, fearful the incessant aftershocks might collapse the darkened crevice he was trapped in.

And then, "all of the sudden I saw light," he said, recounting the moment on Thursday he was pulled from a hole at the bottom of what was once a seven-storey building in Kathmandu.

Tamang did not know whether he was alive or dead. "I thought I was hallucinating," he said.

The improbable rescue was an uplifting moment in Nepal, which has been overwhelmed by death and destruction since the 7.8-magnitude earthquake hit on Saturday.

Early today, the government said the toll from the tremor, the most powerful recorded here since 1934, had risen to 6,198 dead.

After night fell, police reported another dramatic rescue - a woman in her 20s, Krishna Devi Khadka, was pulled from a building in the same neighbourhood as Tamang near Kathmandu's main bus terminal.

"Life has become a struggle to survive. It gives us hope," Hans Raj Joshi said after watching Tamang's rescue.

"We thought they were only bringing out the dead. It's hard to believe people are still alive."

When Tamang was finally extricated, rescue workers inserted an IV in his arm, propped him onto a yellow plastic stretcher - the same kind that has helped convey countless dead - and carried him through the ruins on their shoulders as if he was a newly crowned king.

Lines of police stood on both sides, keeping back mobs of bystanders and journalists. A dazed Tamang, wearing a dark shirt with the New York Yankees logo and the words "New York Authentic," blinked at the bright sky.

When the procession turned a corner and entered the main road outside, there came a sound Kathmandu had not heard in days: the jubilant cheers of thousands of ecstatic onlookers.

Nepal, however, is far from normal. More than 70 aftershocks have been recorded in the Himalayan region by Indian scientists in the past five days, according to JL Gautam, the director of seismology at the Indian Meteorological Department in New Delhi.

Anxiety over the aftershocks and worries over the fate of relatives have caused many to leave the capital. Thousands have boarded buses provided by the government to their rural hometowns.

"I have to get home. It has already been so many days," said Shanti Kumari, with her seven-year-old daughter, who was desperate to see family in her home village in eastern Nepal.

Although small shops have begun reopening, and the once ubiquitous tent cities have begun thinning out, an air of desperation remains.

"We're still feeling aftershocks. It still doesn't feel safe," said Prabhu Dutta, a 27-year-old banker from Kathmandu.

Tamang told his story to a group of reporters inside a tent at an Israeli field hospital. He looked weak and tired. His dark hair was dishevelled. But otherwise he seemed fine.

When Saturday's quake began at 11.56am local time, Tamang said he was having lunch with a friend in the hotel where he worked.

As he ran down toward the way out, the stairs shook. He saw walls cracking, ceilings caving in.

He was in the basement when "suddenly the building fell down. I thought I was about to die," he said. Tamang fainted, and when he regained consciousness, he could see little but darkness.

He was buried face down in a tiny crevice deep in the rubble, and terrified. He could barely move.

Tamang survived on cans of ghee, or clarified butter. He rested his head on chunks of concrete and broken piece of corrugated aluminium roof.

Finally, on Thursday, one Nepalese team began combing the rubble in Tamang's neighbourhood, a place they had found another survivor on Monday.

They cried out and knocked on broken concrete slabs, and then listened closely for any response.

Mostly there was silence. But when an officer named L Bahadu Basnet, shouted "Is anyone there?" he was shocked to get a reply.

"Who is there? Brother, I am here!" Tamang shouted back weakly.

The team used a car jack to help ensure a slab above the rectangular entrance did not cave in.

Mr Basnet took off his helmet, put on a headlamp, and crawled on his arms 10ft inside, pushed in by his colleagues.

He could see Tamang wedged lying down in a crevice behind a motorcycle, and was shocked how responsive he was.

"He thanked me when I first approached him," the officer said. "He told me his name, his address, and I gave him some water. I assured him we were near."

It took a few hours to delicately clear the way for Tamang to be lifted out. Police said Tamang asked for one thing while he waited - juice.

At the Israeli field hospital, doctors X-rayed Tamang and injected him with glucose.

Libby Weiss of the Israeli Defence Forces said he was dehydrated but lucid and "in remarkably good shape," with no other injuries except scratches.

She said: "It's a miracle. I think it's an amazing thing to see in the midst of all this calamity."

Naryan Pandey was one of the spectators standing on the main street outside when Tamang was carried out.

"I'm surprised he's still alive. We've seen dead bodies coming out of the rubble for five days," he said.

"But it doesn't change what we are going through. I've barely eaten. We don't have enough water. I'm hungry."

And then he added, eyeing the rubble beyond: "My friend is still in there. He was a cook. He's still there."