Police have identified the student as Cade Poulos, an eighth-grader at Stillwater Junior High.
Stillwater Police tell KRMG the shooting happened around 8:00 a.m. inside the school.
Immediately after the shooting, the school was put on lockdown, and students were bussed off campus to the nearby Cimarron Plaza shopping center.
Parents were instructed to pick up their kids from Cimarron Plaza around 9:00 a.m.
Skyline Elementary School was also placed on a temporary lockdown, but it and the rest of the schools in Stillwater, except for the junior high, resumed class and are supposed to keep a normal schedule for the day.
Stay with AM 740 and FM 102.3 News Talk KRMG and KRMG.com for the latest on this breaking story.