Jen Hardy was distributing supplies Tuesday in a remote area of Nepal for Catholic Relief Services when the ground began shaking again.
Nearby buildings collapsed. Hardy was in a mango grove, where the danger was less. An elderly woman near her burst into tears. Hardy embraced the woman, trying to comfort her.
"It showed how traumatized they were," Hardy, in her second full week in the South Asian nation, said in a telephone interview from Gorkha, in the central part of the country. "People are just tired. They're scared. ... They don't know when it will stop."
Weeks after a 7.8-magnitude earthquake devastated Nepal — leveling ancient buildings, leaving more than 8,000 dead and displacing hundreds of thousands — a 7.3-magnitude aftershock shook the country Tuesday.
The new earthquake, centered midway between Kathmandu and Mount Everest, killed dozens and spread more fear and misery.
A U.S. Marine Corps helicopter carrying six Marines and two Nepalese soldiers was reported missing while delivering disaster aid in northeastern Nepal, U.S. officials said. There have been no indications the aircraft crashed.
Catholic Relief Services and Lutheran World Relief sent aid workers and supplies to Nepal after the first quake. They had reached about 30,000 people when the second quake struck.
With monsoon rains expected in a few weeks, they are now assessing how the new quake will affect their attempts to get victims to shelter.
Tuesday's quake struck hardest in the foothills of the Himalayas, triggering landslides, and shook the capital badly, sending thousands of terrified people into the streets.
At least 37 were killed and more than 1,100 injured, according to the Home Ministry. The toll was expected to rise as reports reached Kathmandu of people in isolated Himalayan towns and villages being buried under rubble, according to the U.N. Office for the Coordination of Humanitarian Affairs.
The earthquake that hit April 25 killed more than 8,150 and flattened villages, leaving hundreds of thousands homeless.
Impoverished Nepal appealed for billions of dollars in aid from foreign nations, as well as medical experts to treat the injured and helicopters to ferry food and temporary shelters to hundreds of thousands left homeless amid unseasonal rains.
Rescue helicopters were sent to mountain districts where landslides and collapsed buildings might have buried people, the Nepalese 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 the town of Chautara, in Sindhupalchowk, which had become a hub for humanitarian aid after last month's earthquake, the country's worst since 1934.
Tuesday's quake was deeper, from a depth of 11.5 miles with the earlier one at 9.3 miles, and was followed closely by at least 10 strong aftershocks, the U.S. Geological Survey said. Shallow earthquakes tend to cause more damage.
Early reports indicated at least two buildings had collapsed in Kathmandu. At least one had been unoccupied after sustaining damage April 25. Experts say the earlier quake caused extensive structural damage in buildings that did not topple and that many could be in danger of collapse.
Frightened residents in the capital, who had returned to their homes only a few days ago, again set up tents Tuesday night with plans to sleep in empty fields, parking lots and on sidewalks.
Ram Hari Sah, a 40-year-old produce vendor, searched for a spot to pitch an orange tarpaulin to shelter his family.
"Everyone was saying the earthquakes are over," he said. "Now I don't want to believe anyone. We are all scared; we are terrified. I would rather deal with mosquitoes and the rain than sleep in the house."
New landslides blocked mountain roads in Gorkha, one of the regions hit hardest April 25. Damaged buildings collapsed with the latest quake.
Baltimore relief organizations have raised money and are still seeking donations. They are trying to figure out how the fresh quake might complicate efforts to get people into shelter before the monsoon rains begin in June.
Tim McCully, an official at Lutheran World Relief in Baltimore, said it is too soon to know the effects of the new earthquake, but further damage could make it difficult to focus on long-term goals, including getting markets reopened and preparing the rural economy for the next growing season.
"It forces us to constantly reprioritize," he said.
Hardy said just a single night of rain Monday made it difficult to reach some areas. When the monsoon storms begin, she said, some areas will be cut off completely.
Work already had been slow because Nepal's airports and other infrastructure were ill-equipped to deal with a large influx of supplies.
Getting a load of goods into the country from Dubai took a week, McCully said. And in hilly Gorkha, Hardy said the only way to get around is in four-wheel-drive vehicles. They are using tractors to pull trailers of supplies.
McCully said the answer will be to double down on Lutheran World Relief's efforts, but there will be no quick remedies.
"This is going to take a long time for people to recover," he said.
The Associated Press contributed to this article.