(CNN) -- A 13-year-old student died of a self-inflicted gun shot wound Wednesday morning at a junior high school in Stillwater, Oklahoma, police said.
Sherry Fletcher, a spokeswoman for the city of Stillwater, said no one else was injured in the shooting at Stillwater Junior High School.
Students were moved to another location so parents could pick them up or buses could take them home, Fletcher said in a statement.
Stillwater police Capt. Randy Dickerson told reporters that a school resource officer had heard the gun shot from an adjacent hallway and raised the alert.
The officer found the 13-year-old boy with a self-inflicted gunshot wound to the head, he said.
He was unable to confirm whether the student had been bullied, saying the investigation had just begun.
The "horribly tragic situation" was an isolated incident, Dickerson said.
Stillwater school Superintendent Ann Caine said there was nothing in school computer records to indicate the teenager had been bullied.
"It is with a huge heart that I offer my condolences to this student's family," she said.
The boy, who was an eighth-grader, had only been at the school for a short time, but staff that knew him said he had "the biggest smile," she said.
The gun shot was heard shortly before 8 a.m. as students were getting ready to go to class, she said.
Caine said the area had been evacuated as quickly as possible and parents alerted.
Other students likely witnessed the shooting, which was in a hallway near lockers and classrooms, Dickerson said.
Some schools in the area were under a temporary lockdown after the shooting.
Stillwater is about 70 miles northeast of Oklahoma City.