Foreign diplomats had warned earlier in the day that there was a threat of attack at Kabul airport, where thousands of people are waiting to be airlifted.
Twin suicide blasts have killed more than 100 people, including 13 US soldiers, outside Kabul airport.
Two blasts and gunfire rocked the area outside the airport on Thursday evening, witnesses said.
Video shot by Afghan journalists showed carnage, with dozens of bodies strewn around a canal on the edge of the airport.
Thursday’s bombings near Kabul’s international airport killed at least 170 Afghans and 13 US troops, Afghan and US officials said, in the deadliest day for American forces in Afghanistan since August 2011.
Earlier, a Taliban official said the toll included 28 of its members.
Adam Khan was waiting nearby when he saw the first explosion outside what's known as the Abbey gate. He said several people appeared to have been killed or wounded, including some who were maimed.
The second blast was at or near Baron Hotel near the airport. The hotel has been a staging point for evacuations, where many people, including Afghans, Britons and Americans, were told to gather in recent days before heading to the airport for airlift.
'Pool of blood'
Ahmedyar, an eyewitness, who was 300 metres away from the blast, said the explosion was very loud and that the civilian casualties are "in hundreds".
"I ran to help those injured in the blast, but could not get close to them. They were all in a pool of blood," he told TRT World.
Footage and pictures shared on Twitter show charred and bloodied bodies scattered in a sewage drain where hundreds of people had waited for hours to verify their documents.
Khan, a witness, who was waiting outside the airport, said the explosion went off in a crowd of people waiting to enter the airport.
Khan, who said he was standing about 30 metres away, said several people appeared to have been killed or wounded, including some who lost body parts.
Chairman of the High Council for National Reconciliation Dr Abdullah Abdullah also calling it a “terrorist attack”.
“I strongly condemn the terrorist attack at Kabul Airport which killed and wounded a large number of the civilians,” he posted on Twitter.
The Taliban condemned the deadly blasts saying the US forces were responsible for security in the area where the explosion occurred.
“The Islamic Emirate strongly condemns the bombing targeting civilians at Kabul airport,” a statement released by the group’s spokesman on Twitter said.
“The explosion took place in an area where US forces are responsible for security.”
I strongly condemn the terrorist attack at Kabul Airport which killed and wounded a large number of the civilians. My thought and prayers are with the victims and their families at this difficult time.— Dr. Abdullah Abdullah (@DrabdullahCE) August 26, 2021
Threat of airport attacks
Western nations had warned earlier in the day of a possible attack at the airport in the waning days of a massive airlift.
They had urged their citizens and others to evacuate the area ahead of the attack, but crowds of Afghans and foreigners thronged the airport area desperate to catch a flight out of the volatile country.
Suspicion for any attack targeting crowds has been on Daesh and not the Taliban, who have been deployed at the airport’s gates trying to control the mass of people.
The US has been backchannelling with the Taliban to get their citizens and other vulnerable Afghans out. US officials in Kabul were giving lists of names to the group to allow to the airport, drawing criticism from US lawmakers in Washington.
We can confirm that the explosion near the Abbey Gate of the Kabul airport has resulted in an unknown number of casualties. We will continue to update.— John Kirby (@PentagonPresSec) August 26, 2021
But just days, or even hours for some nations, before the evacuation effort ends, few appeared to heed the call to stay away from the airport.
Over the last week, the airport has been the scene of some of the most searing images of the chaotic end of America's longest war and the Taliban's takeover, as flight after flight took off carrying those who fear a return to the militants' brutal rule.
Already, some countries have ended their evacuations and begun to withdraw their soldiers and diplomats, signalling the beginning of the end of one of history's largest airlifts.
The Taliban have pledged not to attack Western forces during the evacuation, but insist the foreign troops must be out by America's self-imposed deadline of August 31.
More than 95,000 Afghans and foreigners have fled Afghanistan via the US-led airlift since the hardline Taliban movement took control of the country.