Two suicide bombers and gunmen attacked crowds of Afghans flocking to Kabul's airport Thursday, transforming a scene of desperation into one of horror in the waning days of airlift for those fleeing the Taliban takeover. The attacks killed at least 70 Afghans and 13 USinfo-icon troops, Afghan and US officials said.

The blasts came hours after Western officials warned of a major attack, urging people to leave the airport. But that advice went largely unheeded by Afghans desperate to escape the country in the last few days of an American-led evacuation before the US officially ends its 20-year presence on 31 August.

US officials initially said 11 Marines and one Navy medic were among those who died. Another service member died hours later. Eighteen service members were wounded and officials warned the toll could grow. More than 140 Afghans were wounded, an Afghan official said.

US vows to avenge deaths, says won't stop evacuation

The US general overseeing the evacuation said the attacks would not stop the United Statesinfo-icon from evacuating Americans and others, and flights out were continuing. Gen. Frank McKenzie, head of US Central Command, said there was a large amount of security at the airport, and alternate routes were being used to get evacuees in. About 5,000 people were awaiting flights on the airfield, McKenzie said.

In an emotional speech from the White House, US President Joe Biden said the latest bloodshed would not drive the US out of Afghanistaninfo-icon earlier than scheduled, and that he had instructed the US military to develop plans to strike IS.

"We will not forgive. We will not forget. We will hunt you down and make you pay," Biden said.

Also Thursday, Defence Secretary LLoyd Austin suggested the evacuation will go on and expressed his deepest condolences to the loved ones and teammates of all those killed and wounded in Kabul today."

Terrorists took their lives at the very moment these troops were trying to save the lives of others," he said. We mourn their loss. We will treat their wounds. And we will support their families in what will most assuredly be devastating grief. But we will not be dissuaded from the task at hand.

To do anything less especially now would dishonour the purpose and sacrifice these men and women have rendered our country and the people of Afghanistan, the statement also said.

The State Department says it is tracking roughly 1,000 American citizens who it believes may still be in Afghanistan.

IS offshoot claims responsibility

The Islamic Stateinfo-icon group claimed responsibility for the killings on its Amaq news channel. The IS branch, known as The Islamic State-Khorasan Province after a name for the region from antiquity, said in its claim of responsibility that it targeted American troops and their Afghan allies.

One of the bombers struck people standing knee-deep in a wastewater canal under the sweltering sun, throwing bodies into the fetid water. Those who moments earlier had hoped to get on flights out could be seen carrying the wounded to ambulances in a daze, their own clothes darkened with blood.

The IS affiliate in Afghanistan is far more radical than the Taliban, who recently took control of the country in a lightning blitz. The Taliban were not believed to have been involved in the attacks and condemned the blasts. The extremist IS group has battled the Taliban, which it views as traitorous for agreeing to a peace deal with the United States.

The Sunni extremists of IS, with links to the group's more well-known affiliate in Syriainfo-icon and Iraqinfo-icon, have carried out a series of brutal attacks, mainly targeting Afghanistan's Shiite Musliminfo-icon minority, including a 2020 assault on a maternity hospital in Kabul in which they killed women and infants.

The Taliban have fought against Islamic State militants in Afghanistan, where the Taliban have wrested back control nearly 20 years after they were ousted in a U.S.-led invasion. The Americans went in following the 9/11 attacks, which al-Qaida orchestrated while being sheltered by the group.

US says Taliban not responsible, but leader of ousted govt disagrees

Pentagon spokesman John Kirby said one explosion was near an airport entrance and another was a short distance away by a hotel. McKenzie said clearly some failure at the airport allowed a suicide bomber to get so close to the gate.

He said the Taliban has been screening people outside the gates, though there was no indication that the Taliban deliberately allowed Thursday's attacks to happen. He said the US has asked Taliban commanders to tighten security around the airport's perimeter.

Taliban spokesman Zabihullah Mujahid denied that any attack was imminent at the airport, where the group's fighters have deployed and occasionally used heavy-handed tactics to control the crowds. After the attack, he appeared to shirk blame, noting the airport is controlled by US troops.

Acting president of the country Amrullah Saleh, however, took the opportunity to point out that Taliban has had links with the Islamic State in the past.