A new report reveals one of the staggering costs of 30 months of war in Syria: over 11,000 children have died.

The report from the London-based think tank Oxford Research Group (ORG), Stolen Futures: The Hidden Toll of Child Casualties in Syria, finds that the biggest killer was explosives, being responsible for 71% of deaths.

Small arms fire were responsible for one in four child deaths, and 13- to 17-year-old boys were the most frequent victims of targeting killings such as sniper fire, execution or torture, the report finds.

“The data we analyzed indicates that bombs and bullets alone ended the lives of ten thousand Syrian children,” report co-author Hamit Dardagan said in statement.

The conflict “has had a catastrophic effect on the country’s children. Besides the many whose lives and futures have been stolen from them, many more will have been injured, maimed, psychologically impacted, uprooted from their homes and orphaned,” the report states.