Nine members of one family, including six children, were killed in a US drone strike targeting a vehicle in a residential neighborhood of Kabul, a relative of the dead told a local journalist working with CNN.

The US carried out a defensive airstrike in Kabul, targeting a suspected suicide bomber of the Afghan affiliate of the ISIS (ISIL), known as the Islamic State Khorasan Province, ISKP (ISIS-K), who posed an “imminent” threat to the airport, US Central Command said Sunday, according to CNN.

The youngest killed was a 2-year-old girl, according to a brother of the one of those killed.  They were “an ordinary family,” he said.  “We are not ISIS or Daesh and this was a family home -- where my brothers lived with their families.”

Neighbors and witnesses at the scene of the drone strike in Kabul told CNN that several people were killed, including children.

The US military reportedly acknowledged later Sunday that there are reports of civilian casualties following the strike.

CNN reports that Capt. Bill Urban, spokesman for US Central Command, said in a statement that they know that there were substantial and powerful subsequent explosions resulting from the destruction of the vehicle, indicating a large amount of explosive material inside that may have caused additional casualties. “It is unclear what may have happened, and we are investigating further.  We would be deeply saddened by any potential loss of innocent life," he added.

US forces have been racing to complete their evacuation operation before Tuesday's deadline and under the threat of a new terror attack on Hamid Karzai International Airport in Kabul.  Recall, a suicide bombing outside the airport gates on Thursday killed 13 US service members and at least 170 others.

CNN says Sunday's drone strike on a vehicle is the second by US forces targeting the ISIS-K terror group in the space of three days.  

The Taliban, which is now in control of Afghanistan, reportedly condemned the strike later Sunday, saying the US had violated the country's sovereignty.

The vehicle that was targeted by the US in Sunday's airstrike on Kabul was next to a building and contained one suicide bomber, a US official told CNN.

It remains unclear if the vehicle was intended to be a car bomb, or if the suicide bomber was using it for transport. "It was loaded up and ready to go," the official tells CNN.

ISIS-K has claimed that an ISIS militant carried out the suicide attack, but provided no evidence to support the claim.  US officials have said the group was likely behind the bombing.

According to CNN, the Pentagon said on Saturday that two "high profile" ISIS targets had been killed and another injured in a US drone strike late Friday in Jalalabad, in Afghanistan's eastern Nangarhar province, in a retaliatory strike for Thursday's attack.