US troops are taking control of Kabul’s international airport, while desperate residents try to flee the city after the Taliban seized Afghanistan.
The US military has secured the site and is taking over air traffic control to evacuate American and allied staff.
Other countries are also evacuating staff, including the UK, which has sent troops for the operation.
But commercial flights have mostly been suspended, stranding hundreds of Afghans and other foreign nationals.
The Taliban claimed victory after the government collapsed on Sunday. President Ashraf Ghani has fled abroad.
The militants’ return to rule brings an end to almost 20 years of a US-led coalition’s presence in the country.
Kabul was the last major city in Afghanistan to hold out against a Taliban offensive that began months ago but accelerated in recent days as they gained control of territories, shocking many observers.
The Islamist group was able to seize control after most foreign troops pulled out.
At the weekend US President Joe Biden defended the withdrawal of American troops, saying he could not justify an “endless American presence in the middle of another country’s civil conflict”.
Following the Taliban’s seizure of Kabul, many people headed to the airport.
One video taken by an Afghan journalist on Monday showed crowds running to the airport terminal with children and luggage in tow.
UK Defence Secretary Ben Wallace told the BBC that Kabul airport was divided into a commercial side – which has largely ground to a halt – and a military side, which has now been secured and is working for the various countries evacuating staff.
The US has sent 6,000 troops to assist in the operation.
Thousands of American citizens, locals embassy staff and their families, as well as other “vulnerable Afghan nationals” will be airlifted in the coming days, a US government statement said.
On Sunday night footage showed hundreds of people running to try to get on the last commercial flights out of the city.
Pictures showed crowds of Afghans waiting on the tarmac while US troops stood guard on Monday morning. At one point the soldiers fired in the air to “defuse the chaos”, a US official told Reuters.
Rakhshanda Jilali, a human rights activist who is trying to leave, said: “How can [the Americans] hold the airport and dictate terms and conditions to Afghans?”
“This is our airport but we are seeing diplomats being evacuated while we wait in complete uncertainty,” she told Reuters.
More than 60 countries, including the US and the UK, have issued a joint statement saying the Afghan people “deserve to live in safety, security and dignity”, and that security and civil order should be immediately restored.
They also called on the Taliban to allow anyone who wishes to depart to do so, and to keep roads, airports and border crossings open.
Suhail Shaheen, a member of the Taliban’s negotiating team in Qatar, told the BBC that people in Kabul should not worry and that their properties and lives were safe.
“We are the servants of the people and of this country,” he said.
US helicopters transporting embassy personnel could be heard over the city on Sunday, and there were reports of smoke rising near the embassy compound as important documents were destroyed.
About 600 British troops have been deployed to assist with their own withdrawal mission.
UK Prime Minister Boris Johnson said his priority was getting UK nationals and “all those who have helped the UK effort over 20 years” out of Afghanistan “as fast as we can”.
He called on “like-minded” powers to work together and not recognise any new government without agreement.
Other countries are also evacuating their citizens from Afghanistan, scaling back their presence and in some cases closing their embassies altogether.
Russia is planning to convene an emergency meeting of the UN Security Council to discuss the situation in Afghanistan.
It said it would not be closing its embassy because it has been provided with security assurances by the Taliban.