Police investigated a potential threat at the San Diego Zoo Sunday, but officers found no evidence of danger. Officers received a call regarding the threat at 1:10 p.m. Sunday. San Diego Police Department units already working at the zoo responded alongside additional officers, according to the d epartment. Police searched the area and reviewed surveillance footage for a suspect, but nothing suspicious was found. Details about the type of threat were not immediately available. Department officials said police were maintaining a presence at the zoo. This story uses functionality that may not work in our app. Click here to open the story in your web browser. ...read more read less