A US drone strike targeting a suicide bomber killed ten civilians, all relatives from the same family. The US military said a person with IS-K was the intended target.

The drone strike hit a parked car outside their home on Sunday. Two-year-old Sumaya was the youngest of the victims, reported BBC.

Emal Ahmadi, the father of Sumaya, said he and his family applied to be evacuated to the US and were waiting for confirmation to go to the airport when the drone strike hit. The US, he added, had made "a mistake. It was a big mistake."

His relative, Ahmad Naser, was also killed in the strike. He worked as a translator with US forces.

"It's wrong, it's a brutal attack, and it's happened based on wrong information," said a relative of the victims, Ramin Yousufi. He cried: "Why have they killed our family? Our children? They are so burned out we cannot identify their bodies, their faces."

Pentagon press secretary John Kirby said that they were "not in a position to dispute" reports of civilian casualties and that an investigation into the incident was ongoing.

He defended intelligence about "what we believed to be a very real, a very specific and a very imminent threat" against Kabul's Hamad Karzai International airport from IS-K, IS's Afghan affiliate.

"Make no mistake, no military on the face of the earth works harder to avoid civilian casualties than the United States military, and nobody wants to see innocent life taken," he said.

On Monday, video and pictures showed smoke wafting across the rooftops of Kabul and what appeared to be a burning car on the street.

"We take it very, very seriously, and when we know that we have caused innocent life to be lost in the conduct of our operations, we're transparent about it," said Kirby.

He said on Saturday that the threat to US military personnel at the airport in Kabul remains "active" and confirmed the military would conclude its withdrawal on schedule. "The threats are still very real, they’re very dynamic, and we are monitoring them in real-time," said Kirby of IS-K.

Army Maj. Gen. William D. "Hank," Taylor said the US would continue to conduct counter-terrorism operations in Afghanistan. "Without specifying any future plans, I will say that we will continue to have the ability to defend ourselves," he said.

Taylor acknowledged the Pentagon would leverage its "over-the-horizon capability" to conduct strikes as needed from bases outside of Afghanistan. "We’re going to defend ourselves," he added.

In an earlier statement, US Central Command said there had been a number of "substantial and powerful subsequent explosions" following the drone strike. It said the explosions suggested there had been "a large amount of explosive material inside, which may have caused additional casualties." Command previously said the strike was successful at "eliminating an imminent" threat to Kabul's airport.

The US has been on high alert since a suicide bomber killed more than 169 civilians and 13 US troops outside the airport last Thursday. IS-K claimed responsibility.

Many of those killed hoped to be evacuated from Kabul, which fell to the Taliban on August 15. US Officials warned of subsequent attacks closer to the August 31 withdrawal date.

The US installed and anti-rocket and mortar system to protect the airport from further attacks that intercepted rockets flying over the capital towards the airport Sunday.

"The President was informed that operations continue uninterrupted at HKIA (Kabul airport), and has reconfirmed his order that commanders redouble their efforts to prioritize doing whatever is necessary to protect our forces on the ground," said White House press secretary Jen Psaki in a statement.

No US or Afghan casualties were reported.

The US drone strike destroyed a vehicle carrying "multiple suicide bombers" from Afghanistan’s Islamic State (ISIS K) affiliate, preventing an attack on the airport, according to US officials.

The US State Department released a statement Sunday signed by 100 countries, in addition to NATO and the EU, stating that "they had received 'assurances' from the Taliban that people with travel documents would still be able to leave the country."

"Our mission to continue evacuating those as required and to meet the mission requirement by August 31 is what commanders are executing," said Kirby on Saturday. "We will maintain the ability to defend ourselves and our operations all the way through."