May 25 (UPI) -- U.S. Central Command on Thursday said more than 100 Iraqi civilians in Mosul died in March after a U.S.-led coalition airstrike targeting two Islamic State snipers detonated other explosives.
The incident occurred at about 8 a.m. on March 17 in Mosul's al-Jadidah district after Iraqi security forces fighting the Islamic State on the ground requested a coalition airstrike.
CENTCOM said the international coalition fighting the Islamic State, also called ISIS, ISIL or Daesh, concluded an investigation and "found that the secondary explosion of ISIS-emplaced material triggered a rapid failure of the structure which killed the two ISIS snipers, 101 civilians sheltered in the bottom floors of the structure and four civilians in a neighboring structure."
CENTCOM said 36 other civilians who are in some way associated with the building remain missing.
"Our condolences go out to all those that were affected," Maj. Gen. Joe Martin, commanding general of the Combined Joint Task Force: Operation Inherent Resolve anti-Islamic State coalition, said in a statement. "The coalition takes every feasible measure to protect civilians from harm. The best way to protect civilians is to defeat ISIS."
Investigators in post-explosive analysis found residues common to explosives used by the Islamic State but that were not consistent with the explosive content found in the GBU-38 precision-guided munition used in the airstrike.
Weapons and structural experts then concluded based on modeling that the structural damage to the building occurred in a location other than where the airstrike occurred and that the explosive damage that resulted could not have been caused by a single GBU-38 missile, CENTCOM added.
"The coalition selected a single GBU-38 precision-guided munition as the most appropriate and proportionate means of engagement to neutralize the threat and to minimize collateral damage," CENTCOM said. "The GBU-38's detonation, localized to the top floor of the structure, ignited a large amount of explosive material which, unknown to the coalition, ISIS fighters had previously placed in the house."
Iraq's military previously said explosives rigged by the Islamic State -- rather than airstrikes -- killed the civilians in the incident.