Kathmandu, Nepal: Thousands of fear-stricken people spent the night out in the open as a new earthquake killed dozens of people and spread more misery in Nepal, which is still struggling to recover from a devastating quake nearly three weeks ago that left more than 8,000 dead.

A US Marine Corps helicopter carrying six Marines and two Nepalese soldiers was reported missing while delivering disaster aid in northeastern Nepal, U.S. officials said, although there have been no indications the aircraft crashed.

Home ministry official Laxmi Dhakal said Wednesday that army helicopters were scouring the Sunkhani area, nearly 80 kilometres northeast of Kathmandu, for the missing helicopter.

Most of the casualties Tuesday's magnitude-7.3 quake were in Dokha district, located northeast of Kathmandu, the district's chief government administrator, Prem Lal Lamichane, said Wednesday.

"People are terrorized. Everyone is scared here. They spent the night out in the open," Lamichane said, adding the administration was running out of relief material.

He asked the government to send more helicopters and supplies. There were many injured people in villages, which have been cut off from the main towns because of the landslides triggered by the earthquake.

Tuesday's quake, centered midway between Kathmandu and Mount Everest, struck hardest in the foothills of the Himalayas, triggering some landslides, but it also shook the capital badly, sending thousands of terrified people into the streets.

Nepal's Parliament was in session when the quake hit, and frightened lawmakers ran for the exits as the building shook and the lights flickered out.

At least 65 people were killed in the quake and nearly 2,000 were injured, according to the Home Ministry. But that toll was expected to rise as reports began reaching Kathmandu of people in isolated Himalayan towns and villages being buried under rubble, according to the U.N.'s Office for the Coordination of Humanitarian Affairs.

Tremors radiated across parts of Asia. In neighbouring India, at least 16 people were confirmed dead after rooftops or walls collapsed onto them, according to India's Home Ministry. Chinese media reported one death in Tibet.

The magnitude-7.8 earthquake that hit April 25 killed more than 8,150 and flattened entire villages, leaving hundreds of thousands homeless in the country's worst-recorded quake since 1934. The U.S. Geological Survey said Tuesday's earthquake was the largest aftershock to date of that destructive quake.

Tuesday's temblor was deeper, however, coming from a depth of 18.5 kilometres (11.5 miles) versus the earlier one at 15 kilometres (9.3 miles). Shallow earthquakes tend to cause more damage.

Rescue helicopters were 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 Sindhupalchowk's town of Chautara, which had become a hub for humanitarian aid after last month's quake.

Impoverished Nepal appealed for billions of dollars in aid from foreign nations, as well as medical experts to treat the wounded and helicopters to ferry food and temporary shelters to hundreds of thousands left homeless amid unseasonal rains.

In Washington, Navy Capt. Chris Sims said the missing Huey helicopter was conducting disaster relief operations near Charikot, Nepal.

A nearby Indian helicopter heard radio chatter about a possible fuel problem, said U.S. Army Col. Steve Warren. The Huey, carrying tarps and rice, had dropped off supplies and was headed to a second site when contact was lost, he said, adding that there has been no smoke or other signs of a crash.

A Nepalese air brigade unit had seen the Huey, so Marines in V-22 Osprey aircraft searched unsuccessfully near its last known location for about 90 minutes, Warren said. Members of the Nepalese army are searching on foot because of darkness, he added.

Due to the rugged terrain, the helicopter could have landed in an area where the crew was unable to get a beacon or radio signal out, Warren said.

Tuesday's quake was followed closely by at least 17 strong aftershocks, according to the USGS.

Frightened residents in the capital, who had returned to their homes only a few days ago, once again set up tents Tuesday night to sleep in empty fields, parking lots and on sidewalks.

"Everyone was saying the earthquakes are over. ... Now I don't want to believe anyone," said 40-year-old produce vendor Ram Hari Sah.

Extra police were sent to patrol ad-hoc camping areas, while drinking water and extra tents were being provided, according to Kathmandu administrator Ek Narayan Aryal.

Meanwhile, new landslides blocked mountain roads in the district of Gorkha, one of the regions hit hardest on April 25, while previously damaged buildings collapsed with the latest quake.

Residents of the small town of Namche Bazaar, about 50 kilometres (35 miles) from the epicentre of Tuesday's quake and well known to high-altitude trekkers, said a couple of buildings damaged earlier had collapsed there as well. However, there were no reports of deaths or injuries.

The earth also shook strongly in neighbouring Tibet, unleashing a landslide that killed one person and injured three, according to China Central Television. Two houses collapsed, the state broadcaster said, quoting disaster officials of the regional Tibetan government.