Ten members of one Afghan family were killed following a US drone strike in Kabul, according to relatives.
The drone strike on Sunday was aimed at a vehicle carrying “a substantial amount of explosive material” and heading to Kabul airport, US officials said.
A military official said the strike had caused “significant secondary explosions”.
Zemaray Ahmadi, 36, was killed alongside his sons Zamir, Faisal and Farzad – aged 20, 16 and 12, the family say.
Six of his nieces and nephews are also said to have died; a boy and girl both aged two, girls aged five and seven, a six-year-old boy and a 28-year-old man.
The family say Mr Ahmadi had worked with a foreign organisation in Kabul for 10 years as technical engineer.
A spokesman for America’s Central Command acknowledged reports of civilian casualties.
“We would be deeply saddened by any potential loss of innocent life,” said US Navy Captain Bill Urban.
The US later said it was continuing to assess the situation.
Reports of the deaths come as Islamic State claimed responsibility for a rocket attack on Kabul airport on Sunday.
US officials said its anti-missile system had intercepted five of the rockets.
All American personnel are due to leave Afghanistan on Tuesday, bringing an end to the airlifts prompted by the Taliban’s rapid takeover of the country.
UK efforts to bring back Britons, as well as people who helped the UK during the 20-year campaign, ended on Friday.