"He managed to obtain the gun, put it in his backpack, go to school," Capt. Lori Bender said.
The six-year-old boy and two other students were grazed by a bullet. Police say a recorded video from the school's cafeteria shows a six-year-old boy was trying to cock the handgun.
"He was actually pulling the gun out and showing it, and he was working on sliding it," Bender said.
The boy's finger then got caught and the gun went off. That surprised the boy, so he dropped the gun and it went off again, wounding the three students.
Bender says while the investigation has determined no adult knew the boy had the gun, there could be some culpability for giving the boy access to the gun.
Bender declined to say when or how the boy got the gun, which was identified as a semiautomatic 9 mm Kel-Tec.CPS is part of the investigation. It's trying to determine if the child is safe in his current living environment.
As police continue interviewing key child witnesses, experts remind parents the best way to avoid another such situation is always to lock away weapons.