The woman was holed up in a room at the Plaza Hotel on Fourth Avenue near Broadway shortly after 5:30 a.m., San Diego police Officer Dan Lasher said. Police crisis negotiators were summoned to the scene.
The woman, who at one point was on her hotel room balcony, threatened to commit suicide by cop, according to Lasher.
About three hours later, the woman's boyfriend tackled her to the ground while she was on the phone with police and wrestled the gun away. Police, who were on the phone with the woman, heard the scuffle and the boyfriend's calls for help.
Both the man and woman were detained, but it was not immediately clear if either was arrested.
Streets that were shutdown in the area have reopened. The police activity downtown also caused a service disruption to orange and blue line trolleys, according to the Metropolitan Transit System. Riders were advised to instead use shuttles running between America Plaza and the Civic Center.