University of Minnesota officials are urging students to be cautious after the school's Interfraternity Council received a letter earlier this week threatening students who belong to fraternities.
In the letter to chapter presidents, U officials warned students to secure their house windows and lock doors, and avoid walking alone at night.
The U Police Department is collaborating with the office of Fraternity and Sorority Life and the Office for Student Affairs to warn and protect students.
"It's being treated as a threat targeting fraternities and their members," U spokesman Steve Henneberry said. "The police department is actively investigating this threat."
The Office for Student Affairs along with Student Counseling Services and the U Police Department held a drop-in support event for concerned students on Friday.
The Interfraternity Council cautioned students not to wear their Greek letters until further notice.
"We are continuing to provide support and keep a watchful eye," said Lamar Hylton, U assistant vice provost for student life.