PENTAGON - The commander of American forces in Iraq says the U.S. military likely played a role in an airstrike in Mosul, an attack March 17 that witnesses said killed about 100 civilians.
"Because we struck in that area, I think there is a fair chance that we did it," Army Lt. Gen. Stephen Townsend, the commander leading the counter-Islamic State fight in Iraq and Syria, told reporters in a conference call Tuesday from Baghdad.
Townsend said Iraqi military leaders "firmly believe" that civilians were gathered by Islamic State ahead of the strike, either to lure the coalition into a trap that would kill civilians or possibly for the extremists' use as human shields.
"We know that ISIS were fighting from that position, from that building, and there were people [whom] you really can't account for in any other way on why they would be there, unless they were forced there," Townsend said, using an acronym for Islamic State group.
Further questions of U.S. involvement have been raised based on the amount of damage in the area where civilian casualties were reported. According to Townsend, the munitions used during the U.S. airstrike should not have collapsed an entire building. Since the building did collapse, that "actually contradicts" the conclusion that the U.S. military was responsible, he said.
Another U.S. official who spoke to VOA on condition of anonymity said: "For example, and just as an example without getting into specifics, but a 50-pound [23-kilogram] precision munition isn't going to bring down a four-story building."
Air Force Brigadier General Matthew Isler, an experienced strike pilot, has been appointed to lead the civilian casualty credibility assessment of the March 17 attack. Townsend said U.S. personnel have inspected the site to conduct tests and gather information.
As U.S. forces continue targeting Islamic State militants to help Iraqi forces retake Mosul, the U.N. human rights chief is calling on Iraq's military and the U.S.-led coalition to review their tactics in the battle.
"The conduct of airstrikes on ISIL locations in such an environment, particularly given the clear indications that ISIL is using large numbers of civilians as human shields at such locations, may potentially have a lethal and disproportionate impact on civilians," Zeid Ra'ad Al Hussein said in a statement Tuesday, using another acronym for Islamic State.
The U.N. says at least 307 people were killed and 273 others wounded between February 17 and March 22 in western Mosul. It attributed the casualties to all sides involved in the fight for western Mosul: Iraqi and coalition airstrikes, Islamic State shellfire, and improvised explosive devices detonated by the militants.
The Islamic State strategy "of using children, men and women to shield themselves from attack is cowardly and disgraceful," Zeid said. "It breaches the most basic standards of human dignity and morality."
WATCH: Iraq continues Mosul offensive
He welcomed pledges by the U.S.-led coalition and Iraqi military that the most serious incidents involving civilian casualties would be thoroughly investigated.
"I'm not targeting civilians; ISIS is," Townsend said Tuesday. "The best way, though, to put an end to this human suffering is to win in Mosul and to win in Raqqa [Islamic State’s headquarters in Syria], and to do it fast."
The U.S. military has said it is looking at more than 700 separate video feeds covering 10 days of airstrikes in its attempts to determine the credibility of reports that coalition strikes killed as many as 100 civilians in Mosul. The Pentagon has called such a civilian death toll a terrible tragedy.
Nate Rabkin, managing editor of the website Inside Iraqi Politics, said the building in question was the home of a wealthy man who had invited refugees to stay there.
"Fighters from ISIS set up on the roof of this building, and so when the building was targeted with an airstrike, it ended up killing a lot of the people sheltering inside," Rabkin told VOA.
More than a half-million civilians are still believed to remain in Islamic State-held areas of Mosul, with many of them used by Islamic State extremists as human shields as Iraqi forces advance.
Civilians, humanitarian aid groups and monitoring officials have warned about the possibility of increased civilian casualties because of a growing demand for airstrikes and artillery.
VOA’s Victor Beattie contributed to this report.