The University of North Carolina (UNC) - Chapel Hill placed its campus on lockdown Monday morning due to reports of an armed gunman.

According to CNN, sirens blared and people on campus were urged to take shelter while police arrived on campus. However, the school lifted the lockdown half-an-hour later and issued an "all-clear" notice.

Police reportedly sought a gunman near the school's Army ROTC and chemistry buildings.

"After thorough search, Police sounded the "All Clear" related to a report of an armed individual near the campus NROTC Building and Venable Hall this morning," UNC said in an emergency statement posted to its website. "The campus community has been asked to resume all normal activities. UNC Police believe there is no verified, ongoing threat to the campus community at this time."

Jim Gregory, a university spokesman, told The Associated Press "an abundance of caution" led the school to issue a lockdown. He did not specify what led the police to deem the campus safe so quickly.

"There's no reason to believe there's any threat to campus at all ever really," Gregory told The AP, "but that's what happens on a college campus and safety is taken seriously."