The University of North Carolina, Chapel Hill temporarily activated its emergency alert system after an unconfirmed report of an “armed and dangerous” person near the ROTC Building, the school said Wednesday morning.

Students, professors and staff had been asked to shelter in place in whatever building they were in on the campus, the university tweeted shortly before 9:15 a.m. local time.

All classes and campus activities were temporarily suspended, the tweet stated.

But about 10 minutes later, the university posted an “all clear,” indicating the emergency was over and all normal activities would be resumed.

A spokesperson for the school later told CNN that reports of an armed person on or near the campus turned out to be unsubstantiated.