“There are other people on the battlefield, too,” he said. “It’s close quarters.”
American officials said that even the timing of the strike was still in question. Col. Joseph E. Scrocca, a spokesman for the American-led command in Baghdad, said in a statement Friday that the strike under investigation happened between March 17 and Thursday.
The civilian death toll in Mosul was already widely described as heavy on account of Islamic State snipers and bombs, and intensified urban fighting in which artillery has been used. But there have been numerous reports from witnesses, including rescue workers and residents fleeing the fighting, about bodies being buried under rubble after heavy air bombardment.
Many of the reports centered on the Mosul Jidideh neighborhood, where residents said airstrikes hit a number of houses in recent days, killing dozens, including many children.
Capt. Ahmed Nuri, a soldier with Iraq’s elite counterterrorism forces, who work closely with the American military and call in airstrikes, said on Thursday that his men, facing heavy sniper fire, helped collect five bodies from the rubble of a destroyed home. He said four of them were brothers — named Ali, Omar, Khalid and Saad — whose bodies were delivered to their grieving mother.
The mother, Captain Nuri said, identified the fifth dead body as that of an Islamic State sniper who had been firing at advancing Iraqi forces from the roof of their house.
Local officials have reacted with outrage at the latest civilian deaths, warning that they will make it more difficult to fully take the city, and will alienate civilians still in Mosul, whom the Iraqi government is counting on for assistance.
“The repeated mistakes will make the mission to liberate Mosul from Daesh harder, and will push civilians still living under Daesh to be uncooperative with the security forces,” said Abdulsattar Alhabu, the mayor of Mosul, using the Arabic acronym for the Islamic State.
Mr. Alhabu estimated that at least 200 civilians had been killed in airstrikes in recent days in Mosul.