The teen was taken to the hospital, where he died and a 16-year-old student was taken into police custody. The death was the first homicide in St. Paul in 2023, Ernster said.
Investigators have not determined a motive for the attack, he said.
MINNESOTA BOAT FACTORY WORKERS SUBDUE ACTIVE SHOOTER
Police cars at the scene of a fatal stabbing in Harding High School in St. Paul, Minnesota where a student was killed and another was arrested. (KSMP)
Minnesota Gov. Tim Walz said he has a child that attends school in St. Paul.
"As the dad of a St. Paul student, I’m heartbroken for the Harding High School community and the family of a student who lost their life today," he tweeted. "We have offered our full support and have been assured that the area is now secure."
The St. Paul Federation of Educators identified the victim as a 10th grader.
"On a personal level as a teacher and a parent, I'm enraged," union President Leah VanDassor said in a statement posted on Facebook. "I know there have been far too many similar incidents around our country that have left many of us heartbroken and hopeless."
The union asked all staffers to wear the Harding school colors of maroon and gold starting Monday to show support for the community.
Fox News Digital has reached out to St. Paul Public Schools for comment.