BOMBED BUILDING HAD EXPLOSIVES PLANTED WITHIN

A U.S. bomb that dropped on a building in the Iraqi city of Mosul set off explosives that had placed inside by Islamic State fighters, causing the structure to collapse and killing more than 100 civilians, a U.S. military investigation concluded Thursday.

The 227-kg bomb dropped by a U.S. aircraft on March 17 was intended to kill two ISIL snipers who posed a threat to Iraqi counterterror forces, the lead investigator, U.S. Air Force Brig. Gen. Matthew Isler, said in a briefing.

The probe found that the U.S. bomb triggered secondary blasts from devices planted in the lower floors, Isler said. It was likely the largest incident of civilian deaths since the U.S. air campaign against ISIL began in 2014.