Mark Opgrande, spokesman for the Oklahoma County sheriff, said the unidentified 14-year-old suspect is in custody.
"They were having an all-school assembly ... when for some reason a male student allegedly stood up and started stabbing a female student. Right now we don't have a motive," Opgrande said.
Opgrande said the girl, who also was not identified, was in stable condition after being stabbed "multiple times ... five, six, seven times" by the boy at Luther High School. Opgrande said he did not know what weapon was used.
Luther Police Chief David Randall said there was no known relationship between the boy and girl or any indication that they knew each other.
Randall said the boy "was stopped and detained by students and staff" following the incident and was later arrested for assault and battery with a deadly weapon. He said the boy was transported to the Luther Police Department and that his father asked that an attorney be present before he was questioned.
However, Randall said that the boy made statements while he was being transported.
"During the drive he blurted out some statements that made no sense," Randall said. "He said he was hired by someone but that he could not discuss it."
School officials did not immediately return phone calls for comment.
The school has just over than 800 students, according to Oklahoma State Department of Education online records. Luther is a town of about 1,200 people about 25 miles (40 kilometers) northeast of Oklahoma City.
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