BOISE, Idaho (AP) — Authorities say they are trying to determine what prompted a young girl to open fire at a rural Idaho middle school, one of the few school shootings in which the suspect is female. Police say the girl pulled a handgun from her backpack Thursday morning and shot two other students and an adult custodian. All three victims were shot in the extremities, and none had life-threatening injuries. Jefferson County Sheriff Steve Anderson says the investigation is likely to take a “considerable amount of time.” Figures compiled by the group The Violence Project show girls and women commit just 2% of both mass shootings and school shootings in the U.S.