US forces in Afghanistan conceded on Saturday that their air strikes in the northern province of Kunduz had "very likely" resulted in civilian killings.
At least 32 people, including babies, children and women, were killed and dozens wounded on Thursday when their houses on the outskirts of Kunduz city were bombed as they slept.
The killings sparked angry protests in the village of Boze Qandahari calling to bring the perpetrators to justice.
The strikes were in support of US and Afghan forces during an attack targeting senior Taliban commanders, according to local officials.
US military spokesman Charles Cleveland said an initial probe showed the attack "very likely resulted in civilian casualties".
General John Nicholson, commander of US forces in Afghanistan, also admitted that the strikes had "likely" caused the loss of innocent lives.
"We will work with our Afghan partners to investigate and determine the facts and we will work with the Government of Afghanistan to provide assistance," he said in a statement.
'What was their crime?'
The carnage triggered impassioned rallies in Kunduz city, with the victims' relatives parading mutilated bodies of dead children piled into open trucks through the streets.
"Look around me, everyone is in deep pain," Sultan Mohammad told AFP news agency, carrying the body of a victim for the mass funeral ceremony on Friday.
"What was their crime? Why were they killed like this?"
"Ordinary people were sleeping in their homes," another protester said. "All night the airplanes were bombing ... What did those children do wrong? I want justice for the killers."
The civilian killings underline the precarious security situation around Kunduz, which Taliban fighters came close to over-running last month, a year after they briefly captured the city in their biggest success in the 15-year long war.
The strikes also killed some top Taliban commanders, defence ministry spokesman Daulat Waziri said.
"Some civilians killed were members of their families," he added.
Civilian casualties caused by NATO forces have been one of the most contentious issues in the campaign against the Taliban, prompting strong public and government criticism.