A bomb threat near or in Schlow Centre Region Library was called in to dispatchers late Tuesday, State College police Capt. Matthew Wilson said.
Police set up a perimeter on South Allen Street from East Foster to College Avenue, blocking all pedestrian and vehicular traffic.
Police say a person also called and threatened to shoot officers who established the perimeter in response to the threat.
Police do not know if the threat was legitimate, but say they are taking it seriously and sweeping the area as part of the investigation.
Penn State sent out an alert to students about the situation, cautioning them to avoid the 100 block of East Beaver Avenue and the 200 block of South Allen Street.
State College, Ferguson Township and Penn State police, as well as Alpha Fire Company responded to the scene.