Louisiana State University returned to normal operations Tuesday afternoon about two hours after officials warned of a report of an armed intruder.
An investigation "determined there was no threat," the university tweeted just before 6 p.m. ET.
Earlier, the university posted a message on Twitter saying an armed intruder had been reported in Coates Hall and police were on the scene. Coates Hall houses academic departments and several student support services, according to the LSU website.
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The tweet advised students and others on the Baton Rouge campus to run, hide or fight. In a later post, university officials said: "The situation is ongoing. No shots have been fired, and there are no injuries. Continue to avoid the area or remain in a safe place."
Classes are not in session at the state's flagship university, but many students have been moving back to the school after summer break.
Police had cordoned off an area around the building with tape and several officers were present, but life on the campus appeared to go on without disruption. Students mingled at the student union across the street, and traffic flowed normally.