Suicide bombers have struck the crowded gates of Kabul airport with at least two explosions on Thursday, causing a bloodbath among civilians, killing 11 US marines and a Navy medic and effectively shutting down the Western airlift of Afghans desperate to flee.
There was no complete death toll, but video images uploaded by Afghan journalists showed dozens of bodies of people killed in tightly packed crowds outside the airport.
A watery ditch by the airport fence was filled with bloodsoaked corpses, some being fished out and laid in heaps on the canal side while wailing civilians searched for loved ones. The Pentagon said "a number" of American service members were killed. Sources said at least 11 marines and a Navy medic were dead.
The Defence Force says all New Zealand personnel involved in the mission in Afghanistan are safe following the attacks.
Islamic State claimed responsibility for the attack, the group's Amaq News Agency said on its Telegram channel.
A suicide bomber from the Islamist militant group "managed to reach a large gathering of translators and collaborators with the American army at 'Baran Camp' near Kabul airport and detonated his explosive belt among them, killing about 60 people and wounding more than 100 others, including Taliban fighters," it said.
US President Joe Biden, his voice breaking with emotion, has vowed the US would hunt down those responsible for the explosions and said he has asked the Pentagon to develop plans to strike back at them.
Biden spoke hours after the blasts killed at least a dozen American troops and scores of civilians, the worst day of casualties for US forces there in a decade.
"We will not forgive, we will not forget. We will hunt you down and make you pay," Biden said in remarks at the White House.
He promised US evacuations would continue. He gave no indication of a change in next Tuesday's US pullout target.
"I have also ordered my commanders to develop operational plans to strike ISIS-K assets, leadership and facilities. We will respond with force and precision at our time, at the place we choose and the moment of our choosing," Biden said.
Biden appeared to be fighting back tears and his voice cracked with emotion as he talked about the American "heroes" who died. "It's been a tough day," he said.
The president said he had told the US military that he would grant additional force if they needed it: "Whatever they need, if they need additional force, I will grant it."
Biden defended his handling of his most serious foreign policy crisis, saying ultimately it is his responsibility, while assigning some blame to his predecessor, Republican Donald Trump, for the 2020 agreement Trump negotiated with the Taliban.
"I bear responsibility for, fundamentally, all that's happened of late," Biden told reporters when asked if he was responsible for the events of the past two weeks.
He said he did not trust the Taliban but believed it was in the group's interest to let the evacuations continue.
Airflifts complete for some
Several Western countries said the airlift of civilians was now effectively over, with the US having sealed the gates of the airport leaving no way out for tens of thousands of Afghans who worked for the West through two decades of war.
The explosions took place amid the crowds outside the airport who have been massing for days in hope of escaping in an airlift which the United States says will end by Tuesday, following the swift capture of the country by the Taliban.
A witness who gave his name as Jamshed said he went to the airport in the hope of getting a visa for the United States.
"There was a very strong and powerful suicide attack, in the middle of the people. Many were killed, including Americans," he said.
Zubair, a 24 year-old civil engineer, who had been trying for a nearly week to get inside the airport with a cousin who had papers authorising him to travel to the US, said he was 50 metres from the first of two suicide bombers who detonated explosives at the gate.
"Men, women and children were screaming. I saw many injured people - men, women and children being loaded into private vehicles and taken toward the hospitals," he said. After the explosions there was gunfire.
Pentagon spokesperson John Kirby said on Twitter: "We can confirm that the explosion at the Abbey Gate was the result of a complex attack that resulted in a number of US and civilian casualties. We can also confirm at least one other explosion at or near the Baron Hotel, a short distance from Abbey Gate."
Taliban official Suhail Shaheen said there were two explosions in a crowded area managed by US forces. "We strongly condemn this gruesome incident and will take every step to bring the culprits to justice."
The Taliban did not identify the attackers, but a spokesman described it as the work of "evil circles" who would be suppressed once the foreign troops leave.
Washington and its allies had been urging civilians to stay away from the airport on Thursday, citing the threat of an Islamic State suicide attack.
In the past 12 days, Western countries have evacuated nearly 100,000 people, mostly Afghans who helped them. But they say many thousands more will be left behind following President Joe Biden's order to pull out all troops by 31 August.
The last few days of the airlift will mostly be used to withdraw the remaining troops. Canada and some European countries have already announced the end of their airlifts, while publicly lamenting Biden's abrupt pullout.
Airport doors 'closed'
"The doors at the airport are now closed and it is no longer possible to get people in," Norwegian Foreign Minister Ine Eriksen Soereide said.
"We wish we could have stayed longer and rescued everyone," the acting chief of Canada's defence staff, General Wayne Eyre, told reporters.
Biden ordered all troops out of Afghanistan by the end of the month. He spurned calls this week from European allies for more time.
The abrupt collapse of the Western-backed government in Afghanistan caught US officials by surprise and risks reversing gains, especially in the rights of women and girls, millions of whom have been going to school and work, once forbidden under the Taliban.
Biden has defended the decision to leave, saying US forces could not stay indefinitely.
But his critics say the US force, which once numbered more than 100,000, had been reduced in recent years to just a few thousand troops, no longer involved in fighting on the ground and mainly confined to an air base. It was a fraction of the size of US military contingents that have stayed in places such as Korea for decades.
Violence from Islamic State creates a headache for the Taliban who have promised that their victory will bring peace to Afghanistan at last. Fighters claiming allegiance to Islamic State began appearing in eastern Afghanistan at the end of 2014 and have established a reputation for extreme brutality.
Since the day before the Taliban swept into Kabul, the United States and its allies have mounted one of the biggest air evacuations in history, bringing out about 95,700 people, including 13,400 on Wednesday, the White House said on Thursday.
The Taliban have encouraged Afghans to stay, while saying those with permission to leave will still be allowed to do so once foreign troops leave and commercial flights resume.