The youngest child, Sumaya, was just two years old.
The deadly strike happened days after a terror attack at Kabul airport, amid a frenzied evacuation effort following the Taliban’s sudden return to power.
It was one of the US military’s final acts in Afghanistan, before ending its 20-year operation in the country.
US intelligence had tracked the aid worker’s car for eight hours, believing it was linked to IS-K militants – a local branch of the Islamic State (IS) group, US Central Command Gen Kenneth McKenzie said.
The investigation found the man’s car had been seen at a compound associated with IS-K, and its movements aligned with other intelligence about the terror group’s plans for an attack on Kabul airport.
At one point, a surveillance drone saw men loading what appeared to be explosives into the boot of the car, but it turned out to be containers of water.
Gen McKenzie described the strike as a “tragic mistake”, and added that the Taliban had not been involved in the intelligence that led to the strike.
The strike happened as the aid worker – named as Zamairi Akmadhi – pulled into the driveway of his home, 3km (1.8 miles) from the airport.
The explosion set off a secondary blast, which US officials initially said was proof that the car was indeed carrying explosives. However the investigation has found it was most likely caused by a propane tank in the driveway.
Relatives of the victims told the BBC the day after the strike that they had applied to be evacuated to the US, and had been waiting for a phone call telling them to go to the airport.
One of those killed, Ahmad Naser, had been a translator with US forces. Other victims had previously worked for international organisations and held visas allowing them entry to the US. (Courtesy BBC)