Kabul’s international airport was under the protection of foreign forces, including thousands of U.S. soldiers sent to the country to assist in a hasty evacuation

In parts of Afghanistan, there were reports that fighters were searching for people they consider collaborators of the United States and the fallen government.

The morning after the Taliban installed themselves in the presidential palace in Kabul, seizing control over Afghanistan two decades after being toppled from power by the U.S. military, fears intensified Monday about a return to the Taliban’s brutal rule and the threat of reprisal killings.

Kabul’s international airport was under the protection of foreign forces, including thousands of U.S. soldiers sent to the country to assist in a hasty evacuation.

It was a scene of desperation, sadness and panic.

Thousands of Afghans flooded the tarmac Monday morning, at one point swarming around a departing U.S. military plane as it taxied down the runway.

Images of people clinging to the hulking aircraft even as it left the ground quickly circulated around the world. It seemed to capture the moment more vividly than words: a symbol of U.S. military might, flying out of the country even as Afghans hung on against all hope.

Worries pervaded Kabul, the capital, about the potential for violence as the Taliban filled the city and the Afghan government crumbled. President Ashraf Ghani fled the country as the insurgents entered the city Sunday.

In remarkable scenes broadcast on Al-Jazeera, Taliban leaders ensconced themselves in the palace only hours after Ghani fled — taking control over what was once one of the most secure locations in the country and a symbol of the nation that the United States spent so much money and sacrificed so much blood to uphold.

Though not a formal surrender, it might as well have been.

In the video, the head of the Afghan presidential security guard shook hands with a Taliban commander in one of the palace buildings and said he had accompanied the Taliban commander at the request of the senior Afghan government negotiator.

“I say welcome to them, and I congratulate them,” the official said.

Afghan officials in other cities were filmed handing over power to insurgent leaders. Former President Hamid Karzai said he had formed a council with other political leaders to coordinate a peaceful transition to a new Taliban government. Karzai also asked the head of the Presidential Protection Service to remain at his post and ensure that the palace was not looted.

Early Taliban actions in other cities under their control offered a glimpse of what the future might hold. In Kunduz, which fell Aug. 8, they set up checkpoints and went door to door in search of absentee civil servants, warning that any who did not return to work would be punished.

The change in atmosphere in Kabul was as swift as it was frightening for many who thought that they could build a life under the protection of their U.S. allies.

Some in the city said the Taliban had already visited government officials’ homes. They entered the home of one former official in western Kabul and removed his cars and took over the home of a former governor in another part of town.

In other parts of the country, there were reports that fighters were searching for people they consider collaborators of the United States and the fallen government.

Residents of Kabul began tearing down advertisements that showed women without headscarves for fear of upsetting the Taliban, whose ideology excludes women from much of public life.

Some police officers were taken into custody by Taliban fighters, while others were seen changing into civilian clothes and trying to flee.

The Taliban said their forces had entered Kabul to ensure order and public safety.

A member of the Taliban’s negotiating team in Qatar told the BBC that “there will be no revenge” on civilians.

“We assure the people in Afghanistan, particularly in the city of Kabul, that their properties, their lives are safe,” Suhail Shaheen said Sunday night. “There will be no revenge on anyone.”