As Afghanistan’s neighbors, along with other countries in the region and in the West, brace for the possibility of a large-scale refugee crisis driven by the Taliban’s rapid return to national power, the largest share of the displacement crisis is unfolding within Afghanistan’s borders, aid groups say.

As the Taliban took territory in recent weeks, waves of Afghans fled their home provinces on foot and in cars and rickshaws in search of shifting, shrinking government-controlled pockets. In the week before Kabul fell to the Islamist group, tens of thousands of people fled, many of them making their way to the capital, directly or by way of provincial capitals that did not hold out long.

“We are seeing large-scale displacement in what is now a humanitarian emergency,” Christopher Boian, a senior communications officer for the Office of the U.N. High Commissioner for Refugees (UNHCR), told The Washington Post.

Afghanistan already had 3.5 million internally displaced people before the Taliban took over. More than a half-million Afghan civilians have been displaced this year, UNHCR estimates. There were 126,000 newly displaced people in the country between July 7 and Aug. 9 alone — numbers that don’t take into account the days of swelling movement before Kabul’s Aug. 15 fall.

The displacement situation, Boian said, is “fluid,” “moving fast,” “somewhat unpredictable” — and “overwhelmingly happening” inside Afghanistan itself. Of the 550,000 displaced people this year, about 80 percent are women and girls, he said.

Now that the Taliban has control at the national level, and there are few places to flee its fighters within the country, it remains to be seen what share of people will simply go home.

“They, like many of us, thought that Kabul would be held by the government for some period of time, and they saw it as a safe location to run to. That proved not to be the case,” Bob Kitchen, vice president of emergencies and humanitarian action at the International Rescue Committee, told The Post on Thursday.

While Kitchen said his organization is not seeing a large-scale return from Kabul, he doesn’t know how long that will last. His sense is that people are still in Kabul with some hope that they can get out of the country.

The Taliban has restricted access to the airport, where scenes of chaos continued into Friday, with only a trickle of Afghans managing to make their way out.

Kabul’s urban Shahr-e Naw Park has transformed into a shelter for thousands of displaced Afghan people. In the nearly 90-degree heat, some hung up cloth to block the sun and mark out distinct areas. Others found trees for shade. Most have fled with almost nothing — some left behind or lost family, too.

“I want to help my people, but I am helpless because I am also a person that doesn’t have a place to live,” Friba, who asked to be identified only by her first name out of fear for her safety, told The Post after the fall of Kunduz, in the country’s north.

Hours before her home district fell to the Taliban on Aug. 8, she and her two brothers and two sisters fled their Kunduz home by rickshaw to the commercial hub Mazar-e Sharif. But upon their arrival, locals were whispering that Mazar-e Sharif would fall to the Taliban, too. Friba drove to Kabul, the national capital and, at the time, the last major government stronghold. She heard lots of gunfire, she said, and her car was shot at on the drive.

“We lost everything. … We could not carry any clothes, anything to use from Kunduz,” she told The Post. “At that time, we just thought about ourselves — how to arrive to a safe place.”

Without food or a carpet to sit on, Friba said, she joined thousands at Shahr-e Naw Park.

Outside the French Embassy, in Kabul’s center, hundreds of Afghans and foreigners desperate to leave have been camping around the compound, the Wall Street Journal reported Wednesday.

“The embassy had turned into an internally displaced persons camp,” Stéphane Nicolas, operations head for consulting firm ATR, told the Journal. She sheltered in the embassy until Tuesday night. “Behavior changes in this kind of place. Everyone is under shock, they know that they have lost everything, and that if they venture out they may die.”

Many other displaced people are staying along streets, in public buildings, and in homes with relatives and friends. They’re “scattered everywhere,” Kitchen said.

The displaced people are already vulnerable: They have trauma, stress, anxiety and injuries, said Muhammad Zaman, a biomedical engineering professor at Boston University who co-founded its Initiative on Forced Displacement. Malnutrition rates in Afghanistan have long been among the world’s highest. Half of the country’s population needed humanitarian assistance at the start of 2021, according to UNHCR.

And there’s the coronavirus. Afghanistan is in the midst of its third — and worst — wave. “Triple humanitarian crises overlapping each other,” Kitchen said. “There’s a lot of reason to be very worried about the populations in Afghanistan right now.”

The nation has administered only enough doses to have vaccinated about 2.4 percent of its population, the Reuters news agency reported.

Mustapha Ben Messaoud, UNICEF’s chief of field operations and emergency response in Afghanistan, said that one priority is getting displaced people psychological support.

“There is a trauma that is taking place. … They see things that we should not see as children, that we should not see as humans,” he said in a U.N. interview. “They must relearn, understand their environment … not to jump every time there is a noise because they have spent days hearing bombs exploding near them.”

Displaced people congregating in cities usually wait in line for water rations delivered by tankers, and they are unsure when their next meal will come, Messaoud said.

Usually, Zaman’s academic work happens once data appears and subjects can be interviewed, bringing focus to understanding and improving access to services in camps. But that’s not possible right now, Zaman said. Things are happening too fast.

“Right now, we don’t even know if there are camps, or if people are just moving in any direction. There is no organizational structure. That’s the kind of anxiety we are in,” he said. “We don’t even know where the vulnerable are.”

UNHCR released a global no-return advisory, calling on all countries to bar forced returns of Afghan nationals, including rejected asylum seekers. The group made an appeal for the international community to allow civilians fleeing Afghanistan to access their territories, and to ensure the right to seek asylum.

In a position memo, UNHCR noted that Afghan civilians whose asylum claims were rejected in the past may need to be reconsidered if a new asylum claim is submitted, given the changed security situation.

Boian said Wednesday that UNHCR remains operational in nearly two-thirds of Afghanistan’s districts, and is able to access displaced people across all provinces. He said about 200 staff members are in Afghanistan, and “we’re staying there for as long as we can.” Still, access to displaced people in certain parts of the conflict area can be constrained at any given time by the deteriorating security situation.

“It is true, that for our own safety, in some provincial areas, the Taliban asked us to pause operations until order is restored. But we are in daily contact with the local leadership in almost all provinces, and their message is clear: They want us to stay and continue our work in Afghanistan,” UNICEF Afghanistan representative Hervé Ludovic De Lys said Wednesday.