Several children have been killed in a US drone attack that destroyed a car laden with explosives near the international airport in Afghanistan’s capital, Kabul, according to witnesses.

Witnesses told Al Jazeera at least three children were among six civilians who died in Sunday’s attack, while some media reports say nine members of one family – including six children – were among the dead.

AFP, mean while reported, citing Major General Hank Taylor that the US is investigating widespread reports that a number of civilians, possibly nine members of the same family including several children, were also killed in Sunday's drone strike.

"We are aware, reports of civilian casualties and we take these reports very seriously, and we are continuing to assess the situation," Taylor said.

According to Al Jazeera Sunday’s attack was the second by US forces in Afghanistan since a member of the ISIL-affiliated Islamic State in Khorasan Province detonated his explosives at the airport on Thursday, killing dozens of Afghan civilians trying to flee the Taliban-controlled country.

In Kabul, witnesses reported a large blast shaking the neighbourhood where the vehicle was parked and television footage showed black smoke rising into the sky.

Several other media reports also reported civilian casualties.

Dina Mohammadi told AP that her extended family resided in the building and that several of them were killed, including children. She was not immediately able to provide the names or ages of the deceased.

The CNN, meanwhile, also reported nine civilian casualties, including six children. It said all nine victims were members of one family.

According to AFP the Islamic State-Khorasan group claimed the rocket attack on the airport in Afghanistan's capital.

The rockets fell as US troops were racing to complete their withdrawal from Afghanistan and evacuate allies.

The Taliban have fought against the ISIL affiliate in the past and pledged – during negotiations with the US last year – not to allow Afghanistan to become a base for “terror attacks”.