Eric Knox was sentenced on Thursday for a minimum of 18 months and up to 5 years in prison.
Knox, an 18-year-old, took a gun to school with him on January 26, 2018 and reportedly threatened to shoot.
Knox plead guilty to Carrying a Concealed Weapon, Carrying with Unlawful Intent, and three counts of Resisting/Assaulting/Obstructing an Officer.
Knox is accused of having a loaded handgun, a .22 caliber pistol, on him while he threatened a teacher at Western Career Prep High School in Blackman Township, a day before his birthday.
Police later found Knox walking off school grounds on Catherine Street and arrested him after he tried to run from the police. Police say he was carrying a loaded handgun.
"Threats made at a school are taken seriously and will be prosecuted," said Prosecutor Jerry Jarzynka.
The Jackson Co. Sheriff's Department and Blackman Township Public Safety Department investigated the case.