But with Mr. Sayar’s older brother and his family nowhere to be seen, his parents and brother ran back inside.

A few seconds later, another tremor shook the ground of eastern Afghanistan, and the family house collapsed. Around them, the screams and cries of neighbors echoed in the village.

“It was like doomsday for us,” Mr. Sayar said as he rested on a carpet in his cornfield, where he was spending Monday night with the surviving members of his family.

Rescue workers on the ground say it will take days to scour the rubble of villages that, two days after the quake, were still out of reach. The Afghan military has evacuated hundreds of people, the injured and the dead, while U.N. agencies have been working to recommission a helicopter that had been grounded as a result of aid cuts from the United States and other foreign donors.

Reports so far provide an incomplete picture of the devastation that has swept through eastern Afghanistan.

“All the figures that have been announced so far are from the villages where the government and military rescue teams could have access,” said Zahidullah Safi, the director of a district clinic in Kunar Province — one of the worst-hit areas, and where Mr. Sayar’s family lives. “There are some villages which are still under the debris and so far, no government or aid agency has arrived there.”

Sunday’s quake, the second devastating one in less than two years in Afghanistan, has added another layer of calamity on top of the overlapping economic, humanitarian and environmental crises that have all worsened in the South Asian nation over the past few months.

Emergency aid had already become scarcer this year after the United States and other major donors cut, suspended or reduced their humanitarian contributions to Afghanistan. Last year, the United States contributed more than 45 percent of the aid supplied to the country. That all but vanished after the Trump administration decimated the U. S. Agency for International Development and other foreign aid programs.

On Tuesday, Britain said that it would commit about $1.3 million in emergency support for those affected by the disaster. David Lammy, the British foreign secretary, said in a statement that the money would be distributed via the International Federation for the Red Cross and the U. N. Population Fund to ensure that “aid reaches those in need and does not go to the Taliban.”

The European Union is set to work with UNICEF, according to Sherine Ibrahim, the Afghanistan director for the International Rescue Committee, a nonprofit organization. The U.N. office for humanitarian affairs said it had unlocked $5 million in emergency funds.

A report by the U.S. Special Inspector General for Afghanistan Reconstruction published last month found that “the Taliban use every means at their disposal, including force, to ensure that aid goes where they want it to go, as opposed to where donors intend.”

“A lot of help and assistance is still needed,” said Homa Nader, acting head of the International Federation of the Red Cross and Red Crescent in Afghanistan.

This was all too apparent in Kunar’s Mazardara Valley. That was where Mr. Sayar lost seven family members in the quake.

On Monday and Tuesday, villagers and emergency workers searched through for neighbors, relatives and friends, dead or alive. They carried them on makeshift stretchers like bed frames over slopes and through narrow alleys, down to trampled cornfields where helicopters were landing and taking off. They flew back and forth between the devastated areas and the hospitals of Jalalabad, the closest large city, and Kabul, the capital, about 100 miles away.

Khalil Ur Rahman Babakhil, 30, had traveled from Kabul to Mazardara, where his in-laws lived. When he arrived on Monday, he found their house collapsed, and in front of it the bodies of his wife’s parents and three siblings.

“I don’t know how to let my wife know,” Mr. Babakhil said.

Before the earthquake, more than half of Afghanistan’s 42 million people were already in need of humanitarian assistance. In Kunar Province’s remote district of Nurgal, where Mr. Sayar lives, most communities live in extreme poverty, with no steady source of income other than their biannual harvest of corn, which brings them about $220 a year.

About 3.5 million children under 5 are malnourished in Afghanistan, according to UNICEF.

On Tuesday in Kunar Province, children sat in silence in ambulances or walked bewildered among the collapsed homes.

After he escaped the house, he said, he heard his sister-in-law, still inside, screaming in the middle of the night after the second tremor. But in the darkness, and without any tools, the people outside could do nothing to help.

When the sun rose on Monday, Mr. Sayar found her dead, with her son. He also found his parents and younger brother, who had fled the house but then rushed back inside. Now they, too, were dead.

More than 800 people were killed and 2,500 were injured after a 6.0-magnitude earthquake rocked the mountainous areas of eastern Afghanistan on Sunday night, Afghan officials said on Monday. The death toll would probably rise, they added, as rescue workers scrambled to reach communities stranded in isolated valleys hardly reachable by road.

The epicenter of the quake was near Jalalabad, a city of about 200,000 people, but most of the destruction took place in the province of Kunar, north of Jalalabad, where dozens of villages with mud and brick houses were hit. Less than 100 miles away, residents of Kabul, Afghanistan’s capital, felt the aftershocks across the city throughout the night, but no major damage was reported.

The quake was a shallow one, just five miles from the earth’s surface, which made it likelier to be more destructive, as shallower waves retain more of their power when hitting the surface. Soon after the initial shaking stopped, people scrambled in the middle of the night to reach neighbors trapped under the debris of collapsed houses, according to videos shared on social media.

Road access was difficult for rescue workers in the area’s steep terrain, where landslides had struck. Homa Nader, the acting head of the International Federation of the Red Cross and Red Crescent in Afghanistan, said it took Red Cross teams from Jalalabad four hours overnight to reach the most affected area, in Nur Gal district, just 35 miles away. By Monday afternoon, the road linking Jalalabad, one of Afghanistan’s largest cities, to Kunar Province had reopened, and a steady stream of ambulances were rushing to the impacted areas while on the other side, dozens were ferrying victims back to Jalalabad.

Zabiullah Mujahid, the Taliban’s chief spokesman, told a news conference in Kabul on Monday that said 800 people had been killed and 2,500 injured in Kunar Province alone. In Nangarhar Province, he said, at least 12 people were killed and 255 were injured.

Earthquakes are a prevalent danger in Afghanistan and other countries in the region, where many people live on or near geological faults. In 2022, a 5.9-magnitude quake that struck a remote area of Afghanistan’s southeast killed at least 1,300 people, according to the United Nations. The Taliban, who have ruled Afghanistan since 2021, said at the time that more than 4,000 people had died.

The quake is the latest in a series of overlapping crises for Afghanistan. Hundreds of hospitals and health care centers have been forced to shut down since the Trump administration suspended U.S. foreign aid earlier this year. More than 2.3 million Afghan nationals have returned to the country, in some cases by force, after being expelled from Pakistan or Iran amid a wave of xenophobia and political pressure in those countries.

One of those Afghans, Said Meer, had planned to arrive in Jalalabad on Monday with his two wives and 12 children, a day after leaving Lahore, the city in eastern Pakistan where he was born and had spent his whole life. He was hoping to transfer his livestock business to Jalalabad.

On Monday, the colorful truck carrying Mr. Meer’s extended family and their meager belongings was at a border crossing, waiting to enter Afghanistan.

“May God watch over our Afghan people,” Mr. Meer said by telephone. “War, earthquakes, poverty — every hardship is a test from God.” Despite the destruction brought by the quake, he said he still planned to move to Jalalabad, 40 miles from the border.

In Pakistan, tremors were felt across several districts of the northwestern border province of Khyber Pakhtunkhwa, as well as in parts of Punjab Province, the Pakistan-administered part of Kashmir and the capital, Islamabad, the Pakistan Meteorological Department said. No major damage or casualties had been reported in Pakistan so far, officials said.

Since the Taliban returned to power, international assistance has gradually dwindled. Under President Trump, the United States, which last year provided 45 percent of the aid supplied to Afghanistan, has suspended or eliminated nearly all of its contributions. Several other European countries, including Britain, France and Sweden, have also cut back on assistance.

The Taliban have repeatedly called on foreign governments and businesses to finance Afghanistan’s reconstruction from four decades of war, but only Russia has formally recognized them as the country’s official government. As of Monday afternoon, Iran, India, Japan and the European Union had committed support to the victims of the earthquake, the spokesman for the Taliban-run Ministry of Foreign Affairs, Hafiz Zia Ahmad Takal, told The New York Times.

The U.N. Secretary General António Guterres expressed his condolences to the victims’ families and said, “The U.N. team in Afghanistan is mobilized and will spare no effort to assist those in need in the affected areas.”

Zia ur-Rehman contributed reporting from Islamabad, Pakistan.