The daily chaotic scenes of evacuation at Afghanistan's Kabul airport turned into scenes of death and maimed survivors on Thursday as a suicide bomber killed at least 79 Afghans and 13 US troops, bringing more uncertainty and risks to the war-torn land.

The United States said on Friday that a deadly attack at the gate to the airport on Thursday was carried out by one suicide bomber, not two.

"I can confirm for you that we do not believe that there was a second explosion at or near the Baron Hotel, that it was one suicide bomber," Army Major General William Taylor told Reuters.

The Islamic State terrorist group claimed responsibility for the attack, injecting further panic into the final days of an already frenzied US-led airlift.

Taliban spokesman Suhail Shaheen said in a message: "We strongly condemn this gruesome incident and will take every step to bring the culprits to justice."

China on Friday condemned the attack at Kabul airport, saying it is ready to work with the international community to address the threat of terrorism and prevent Afghanistan from becoming a source of terrorism again.

Foreign Ministry spokesman Zhao Lijian said at a daily news conference that the attack showed the security situation in Afghanistan remains complicated and severe. Relevant sides should take effective measures to ensure a smooth transition of the situation there and the safety of the Afghan people and foreign nationals in Afghanistan.

Zhao noted that no Chinese people were killed or injured in the attack.

He also reiterated China's concerns over the East Turkestan Islamic Movement, an international terrorist organization listed by the United Nations Security Council that constitutes a direct threat to the security of China.

US President Joe Biden and General Frank McKenzie, the US general overseeing the evacuation of Afghans, US citizens and others, said that the attack wouldn't halt the US-led airlift.

"We are continuing to bring people onto the airport," McKenzie said at the Pentagon a few hours after the explosion. "The plan is designed to operate under stress."

He also noted that there were still around 1,000 US citizens in Afghanistan.

US Defense Secretary Lloyd Austin said that "we will not be dissuaded from the task at hand", a reference to evacuations from Kabul airport before the Aug 31 deadline set by Biden to leave the Taliban-controlled country.

On Friday morning, some evacuation flights resumed with queues of people seen lining up on the tarmac, but there were no more crowds near the sites of the blast.

The United Kingdom and Spain announced their evacuation operations would end on Friday, after Canada and Australia had already stopped their flights.

The overall organization of the US withdrawal is "very chaotic and hasty", giving terrorists an opportunity to take advantage of the situation to create more chaos, said Dong Chunling, a research fellow at the China Institutes of Contemporary International Relations.

"In the past two decades, Afghanistan has not solved the fundamental problems of domestic power fragmentation, people's livelihoods and well-being that easily lead to the breeding of terrorism," he said. "After the withdrawal, the situation in Afghanistan is more like a pile of dry firewood, which can be ignited by terrorists."

US President Joe Biden said that he had instructed the US military to develop plans to strike IS.

However, Dong said if the breeding ground for terrorism cannot be eliminated fundamentally, the war on terrorism can only be counterproductive.

"In the past two decades, the US has played a leading role in the anti-terrorism war. But the current chaos shows that the country has made mistakes at the strategic level," he said. "If the US does not change its behavior, including pursuing hegemonism and creating clashes of civilizations, the future anti-terrorism situation will not improve."

Agencies contributed to this story.