KATHMANDU: A new earthquake and several powerful aftershocks hit devastated Nepal on Tuesday, killing at least 66 people and injuring thousands, said the Nepal Home Ministry.

Most of the reported fatalities were in villages and towns east of Kathmandu, only just beginning to pick up the pieces from the April 25 quake that left more than 8,000 dead.

The US military's Pacific Command said a Marine Corps helicopter involved in disaster relief had gone missing, with six US Marines and two Nepalese soldiers aboard.

The new 7.3 magnitude quake struck at 12:35 pm Tuesday and was centred 76 km (47 miles) east of the capital in a hilly area close to the border with Tibet, according to coordinates provided by the US Geological Survey (USGS), and unleashed landslides in Himalayan valleys near Mount Everest.

Villagers who watched their homes collapse said they only survived because they were already living in tents.

Aid workers reported serious damage to some villages in the worst-affected Charikot area and said some people were still trapped under rubble. Witnesses said rocks and mud came crashing down remote hillsides lined with roads and small hamlets.

“We still don't have a clear view of the scale of the problem,” said Dan Sermand, emergency coordinator at medical NGO Medecins Sans Frontieres, which surveyed the area by air and saw multiple landslides.

Pakistan expressed sorrow and grief on the loss of lives after the latest earthquake hit Nepal on Tuesday. A Foreign Office spokesman in a statement said the news of a fresh earthquake had shocked and saddened the entire nation of Pakistan.

“Our hearts goes out to the victims of this repeat catastrophe which occurred in such a quick succession when our Nepali brethren were still grappling with the 25th April devastating earthquake,” said the spokesman.

Tuesday's quake was felt as far away as New Delhi, and officials said it caused buildings to collapse in Tibet in neighbouring China.

A second tremor of 6.3-magnitude struck around half an hour later, followed by yet more aftershocks, according to the USGS.

In neighbouring India, at least 17 people were confirmed dead after rooftops or walls collapsed onto them, according to India's Home Ministry.

Chinese media reported one death in Tibet.

In Nepal, at least three people had been rescued in the capital, while another nine pulled to safety in the district of Dolkha. Rescue helicopters had been sent to mountain districts where landslides and collapsed buildings may have buried people, the government said.

Home Ministry official Laxmi Dhakal said the Sindhupalchowk and Dolkha districts were the worst hit.

Search parties fanned out to look for survivors in the wreckage of collapsed buildings in Sindhulpalchowk's town of Chautara.

The International Organisation for Migration (IOM), which has a number of teams on the ground in the wake of the April 25 quake, said four people were crushed to death when buildings collapsed in Chautara, east of Kathmandu.

Nepalese patients are carried out of a hospital building as a 7.4 magnitude earthquake hits the country, in Kathmandu on May 12, 2015. — AFP

The ground swayed for close to a minute from the first of Tuesday's tremors, according to an AFP correspondent in Kathmandu.

“We felt it and suddenly there were huge crowds running up and down,” said resident Suresh Sharma, who was in a vegetable market at the time.

“It was very scary and very difficult to make my way out,” said the 63-year-old.

“The last time we had the big quake I ran out of my house and barely escaped. This one felt just like that one. I can't believe it's happening again."

Read more: Nepal: Experiencing the aftermath

Shaking went on and on

Rose Foley, working in Kathmandu for the UN's children's fund UNICEF, said staff dived under tables. “The shaking seemed to go on and on. We got out to safety as soon as possible. Sitting out in the open it felt like I was on a boat on rough seas as aftershocks hit,” she said by email.

Although the latest quake did not appear to be as severe as the April 25 one, residents were terrified that buildings that were already badly damaged could come crashing down.

“I was thinking of moving to a rented room, but today was so scary I can't risk my family's life,” Dipak Koirala, who has been living under a tent since April 25, said by phone from central Ramechhap district.

“We will continue to stay in the tent but it's wet here and the rain came into the tent, which we are sharing with 24 people. “Kathmandu's Tribhuvan International Airport, the main entry point for flights bringing in aid, was briefly closed again Tuesday as a precaution but reopened after a couple of hours.

Whole villages were destroyed in the April 25 quake while large parts of Kathmandu were destroyed, leaving tens of thousands homeless.

Relief teams from around the world are still working to provide water, food and medical assistance to Nepalis.

Nepalese people gather in a temporary shelter after another earthquake in Bhaktapur, Nepal, Tuesday, May 12, 2015.— AP

Explore: Nepal: Picking up the pieces

Patients wheeled out of hospital

On Tuesday at the main hospital in Kathmandu, patients hurt in last month's quake were brought out in wheelchairs to avoid further injury.

People could be seen frantically calling their families as medical attendants rushed to set up tents in the car park.

The capital was filled with the sound of car horns as desperate residents rushed to get back home to check on loved ones.

Pramita Tamrakar, who had only just reopened her family's furniture store, said she had rushed out onto the street after grabbing her eight-year-old son and 12 year-old daughter.

“I don't understand what is going on,” she told AFP.

“I saw in the news the day before yesterday that the risk was lower, it wouldn't happen again... and today we had a big one. I am very scared. My children are also very scared. “Nepalese police urged people to stay outside and avoid jamming the fragile cellphone network.

The quake was also felt some 1,000 kilometres away in the Indian capital where buildings shook and workers evacuated offices.

Other cities in northern India were also rocked, including Bihar where television footage showed goods toppled over in shop windows.

A Chinese official at the Tibet regional seismological bureau said there had been reports that houses damaged on April 25 had now collapsed.

While nearly all of those killed by the April 25 quake were in Nepal, around 100 victims also died in India and China.

Explore: Tears and prayers for quake-hit Nepal

Family watches house disappear

A family sat on the edge of road where their house had just fallen down the hill, rubble spread over hundreds of feet below.

“We watched it go down slowly, slowly,” said Ashok Parajuli, 30.

In Charikot, where at least 20 bodies were recovered, hotel owner Top Thapa said the quake was at least as strong as last month.

“We saw houses falling, collapsing along the ridge,” said Thapa, owner of Charikot Panorama Resort. He said he saw five or six multi-storey buildings come down.

Politicians dashed for the exit of Nepal's parliament building and office towers swayed as far away as New Delhi.

Parents clutched children tightly, and hundreds of people frantically tried to call relatives on mobile phones. Shopkeepers closed their stores and the streets were jammed with people rushing to check on families.

Elsewhere, people huddled in public spaces, too nervous to venture inside.

“I am very scared and I am with my two sons. The school building is cracked and bits of it, I can see they have collapsed,” said Rhita Doma Sherpa, a nurse with the Mountain Medicine Center in Namche Bazaar, a departure point for trekkers headed to Everest.

“It was lunchtime. All the kids were outside. Thank God.”

'We saw the mountain fall'

May is peak season for climbing and trekking in Nepal's high altitude valleys and peaks, but the usually bustling lodges and tea-houses were close to empty after thousands of tourists fled the April quake.

Dambar Parajuli, president of Expedition Operators' Association of Nepal, said there were no climbers or Nepali sherpa guides at Everest Base Camp.

Mountaineers seeking to scale the world's tallest peak called off this year's Everest season after 18 people died when last month's quake triggered avalanches on the mountain.

“All of them have already left,” Parajuli said.

In Lukla, the departure point for treks to Everest, buildings cracked and small landslides were triggered when the ground shook.

At least three school children were injured.

Susana Perez from Madrid was on a 10-day trek with her husband to Island Peak in the Everest region and was about to reach Lukla.

“We saw the mountain in front of us fall down ─ earth and rocks. There were some houses underneath but it was not clear if they were hit,” Perez said.

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