KABUL — Even as the final U.S. military flights soared out from Kabul’s airport on Monday, friends and relatives in a nearby neighborhood buckled in anguish over the deaths of 10 extended family members in a U.S. drone strike the day before.

The strike was meant to thwart a purported planned attack by the Islamic State. Questions remain about whether the U.S. accomplished its intended mission, but this much is known: 10 civilians in this northwestern Kabul neighborhood — eight of them children 18 and under — were killed in the attack, family members told The Washington Post on Monday, adding to the 48,000 civilian casualties already suffered during the past 20 years of war.

The dead were all from a single extended family who were exiting a car in their modest driveway when the strike hit a nearby vehicle, said Abdul Matin Azizi, a neighbor who saw the attack. Azizi, 20, said the explosion occurred as the family returned home Sunday afternoon around 4:30 p.m.

Azizi said he ran next door to help and found a gruesome scene, the air thick with smoke. “The bodies were covered in blood and shrapnel, and some of the dead children were still inside the car,” he said.

U.S. airstrikes gone awry became an enduring and tragic feature of the war, with their toll on Afghan civilians undermining support among ordinary people and the Kabul government for the American-led military operation that many Afghans came to mistrust. Pledges from the United States to investigate civilian deaths often frustrated Afghans, who felt that justice was rarely done.

The United States “always says they are killing [the Islamic State], al-Qaeda or the Taliban, but they always attack civilian people and children,” said Ahmad Fayaz, a relative of those killed. “I don’t think they are good people.”

U.S. Central Command said the strike Sunday destroyed an Islamic State car bomb that posed an “imminent” threat to Kabul’s airport. It acknowledged reports of civilian casualties and pledged to investigate the incident but did not release specifics. The attack is the second U.S. drone strike on Afghanistan in response to a suicide bombing and gunfire attack outside Kabul’s airport on Thursday.

A U.S. drone strike targeting the Islamic State on Aug. 29, reportedly killed 10 civilians in Kabul including several small children. (The Washington Post)

Mourners gathered at a neighbor’s home under the shade of a grape arbor. A woman, her face raw from sobbing, approached the garden’s entrance in hysterics.

“I lost my daughter, I lost my heart,” she screamed, calling out to God before a group of women surrounded her, trying to calm her down. Suma Ahmadi’s 2-year-old daughter and three of her brothers were killed in the explosion, Fayaz said.

Growing faint and unable to speak, Ahmadi was helped back into the shade. Fayaz said she was inconsolable all night, unable to sleep or eat.

Of the 10 civilians killed, eight were 18 and under, according to lists from family members obtained by The Washington Post. Zamarai Ahmadi, 45, an engineer for a U.S.-based nonprofit, and three of his sons were among those killed, according to one of his surviving sons, 22-year-old Samim Ahmadi.

Zamarai Ahmadi’s employer, Nutrition and Education International, said in a statement released on Monday that “we are all very saddened and shocked by his sudden death.”

The elder Ahmadi had worked for the organization since 2006, according to the statement, “was well respected by his colleagues and compassionate towards the poor and needy. Just yesterday, he, together with us, prepared and delivered soy-based meals to hungry women and children at local refugee camps in Kabul.”

The Taliban condemned the attack and announced it is investigating allegations of civilian casualties.

“No country including the U.S. has the right to carry any direct operation in our country,” Taliban spokesman Zabihullah Mujahid said in a statement Monday. “They should share information with us so that we can take actions by ourselves.”

In announcing its own investigation, U.S. Central Command said it is “unclear what may have happened.” “We would be deeply saddened by any potential loss of innocent life,” the statement said.

The suicide bombing outside Kabul airport Thursday was claimed by the Islamic State. The attack killed 13 U.S. troops and more than 170 civilians trying to flee the country.

The Sunday drone strike that took the lives of the 10 family members “is a glimpse into the future U.S. involvement in Afghanistan if the Biden administration pushes ahead with an ‘over the horizon’ counter-terrorism program that does not prioritize civilian protection,” Paul O’Brien, the executive director of Amnesty International USA, said in a statement condemning the strike and calling for a full investigation.

The Biden administration’s “over the horizon” plan to continue applying pressure on terrorist groups in Afghanistan uses aircraft and surveillance based in the Persian Gulf and other regions. And some criticize the approach as a less precise use of air power because U.S. or allied troops are not observing from the ground to relay intelligence.

“The Americans said the airstrike killed Daesh members,” Azizi, the neighbor, said angrily, using a term for the Islamic State. “Where is Daesh here? Were these children Daesh?”

Haq Nawaz Khan in Peshawar, Pakistan, and Alex Horton in Washington contributed to this report.