Home ministry official Laxmi Prasad Dhakal said at least 65 people had been killed in Tuesday's 7.3 magnitude quake, which destroyed swaths of housing in the district of Dolakha east of the capital, Kathmandu.
Most of the reported fatalities were in villages and towns such as Charikot, the capital of Dolakha, which were only just beginning to pick up the pieces from the massive April 25 quake that killed more than 8,000 people.
That is also where the Marine Corps UH-1Y Huey helicopter participating in earthquake relief operations lost radio contact on Tuesday after its crew was heard talking about fuel problems.
An initial air search before nightfall failed to locate the aircraft and Nepali ground forces were sent into the area to look for the six Marines and two Nepali army personnel on board.
"We are working on tracking them down now," said Marines media officer Cassandra Geseeki. She said the helicopter was delivering humanitarian aid and there was no indication that there were any civilians on board.
Nepali government officials said the search was focused on a village called Sunkhani. Residents in the area spent the night under tarpaulins and in tents, too scared to return to damaged homes as aftershocks rattled the hills.
"Even those houses that have not been flattened have developed cracks. People are too afraid to go into them," said Aula Bahadur Ale, assistant district administrator of Dolakha district.
"It looks live a graveyard here. We are still feeling the aftershocks that make people terrified."