A caller reported the discovery of the mysterious parcel in the lobby of the Front Street building about 2:30 p.m., according to police.
Apparently, no one inside saw who left the package in the library.
Officers shut down a block of the thoroughfare while an explosive-
materials team investigated.
The bomb squad looked over the box and eventually opened it, then called an all-clear about 4:30 p.m., said Maurice Luque, a spokesman for the San Diego Fire-Rescue Department. Police then reopened the street.
During the incident, the nearby downtown jail accepted no new prisoners, instead sending them to Vista Detention Facility.