A US military investigation on has acknowledged that more than 100 civilians were killed in an airstrike on a building in the Iraqi city of Mosul in March during operations against Islamic State militants.
The probe concluded that the US strike in the Al-Jadida district inadvertently triggered explosives placed in the building by Islamic State fighters, causing it to collapse.
Local officials and eyewitnesses have said as many as 240 people may have died in the strike.
It is believed to be one of the single largest incidents of civilian casualties since the US-led coalition started operations against Islamic State in Iraq and Syria.
Air Force Brigadier General Matthew Isler, who oversaw the investigation, told reporters that 101 civilians inside the building were killed, four civilians were killed in the neighbouring building, and 36 civilians were still not accounted for.
News that makes sense
Your trusted source for staying up-to-date with the world around you. Get free daily news updates and analysis, straight to your inbox.
Prior to the March 17 strike, Iraqi forces were about 100 meters away and could see two snipers on the second floor of the building. However, Isler said, there were blind zones and the forces could not see parts of the building.
The coalition had been monitoring the area since the operation for western Mosul began weeks before. However, for two days before the strike took place, the coalition did not have overhead surveillance of the area because of the weather, Isler said.
When the 500-pound bomb was dropped on the building targeting the snipers, it triggered explosives inside the concrete structure, collapsing it onto civilians.
The United States and nearby Iraqi forces did not know there were civilians in the building or that it had been rigged with explosives, the probe found.
"This investigation determined that ISIS deliberately staged explosives and snipers to harm civilians," Isler said.
He added that the coalition took responsibility for the air strike.
Prior to this investigation, the US-led coalition against Islamic State said that at least 352 civilians had been killed in strikes it carried out in Iraq and Syria since 2014. That estimate is far lower than those provided by outside groups.
