Kabul, Afghanistan - The US evacuation mission from Kabul airport entered its final phase on Friday after scores of people were killed in a terrorist attack claimed by an affiliate of the Islamic State group.

Washington and allied countries are rushing to complete their evacuations and troop withdrawals by August 31, a deadline agreed with the Taliban, which took power in the country earlier this month.

According to the British defense minister, 60 to 80 Afghan civilians were killed in the two powerful bomb blasts that struck a perimeter gate and a nearby hotel on Thursday.

The US said 13 of its service members were killed. Dozens of other people were injured.

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The Taliban, on the other hand, initially spoke of only 13 to 20 civilians killed.

The White House said on Friday that Washington and its allies had evacuated 12,500 people from the airport in the past 24 hours, despite the fact that the evacuation mission had been suspended in the wake of the blasts.

The White House said 8,500 people were flown out by the US military directly and 4,000 others were airlifted out in planes belonging to its allies.

Washington added that its evacuation mission had included a total of 105,000 people thus far.

Residents of Kabul expressed horror at the devastating attack on the city's airport, which not only killed US service members but Afghans hoping to flee the country.

"I am frustrated and disappointed," resident Hussain, who lives in the western part of the city and whose last name is being withheld for safety reasons, told dpa on Friday. "Everyone here in Kabul is frustrated and disappointed."

Wahid, a fellow resident who lives not far from the airport, said he was suffering "the worst time" of his life.

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He said that in his discussions with locals, some placed blame for the carnage on the throngs of people who had been converging at the site in a desperate attempt to escape their Taliban-controlled country.

Television images from the attack site showed bloodstained stones and pieces of clothing strewn on the ground.

The square outside the gate, where the crowds of people who had been trying to get on evacuation flights were standing shoulder-to-shoulder when the blasts struck on Thursday afternoon, was deserted. Local hospitals were treating injured victims.

The situation on the ground is rapidly deteriorating, with medical supplies already running short. Planned supply flights by the World Health Organization (WHO) had to be cancelled due to the security situation, according to WHO emergency coordinator for the region Rick Brennan.

"There are only enough supplies for a few more days," Brennan said, describing the fact that 97% of the approximately 2,200 WHO-funded health clinics in Afghanistan continued to function was "a ray of light."

The UN High Commission for Human Rights condemned the attack on Friday, saying that it had clearly been designed to kill and injure as many people as possible.