10News learned a rally staged by the group MoveOn.org was held in front of the building at 1800 Thibodo Road at around noon. Following the rally, a man contacted Issa's office and said a "surprise for the congressman" was left at the scene, a source close to the investigation told 10News.A staff member at the office discovered a suspicious device and contacted the San Diego County Sheriff's Department shortly before 1:30 p.m.Authorities evacuated about 30 people from the building as a precaution, and the sheriff's department's Bomb/Arson Unit responded to the scene, 10News learned.Deputies found a plastic bottle containing some kind of liquid outside the complex, sheriff's Lt. Jim Nolan said.Authorities cleared everyone out of the area, shut down a stretch of the street and called in a bomb squad, which searched the buildings and surrounding grounds with a service dog.About 4:30 p.m., the ordnance team determined that the bottle posed no threat, according to Nolan. Investigators thought the liquid inside it might have been urine, the lieutenant said.Streets were re-opened and the building was ruled safe to re-enter.Members of the MoveOn.org organization told 10News they were unaware of the discovery and denied any responsibility.A group representative said, "About 30 people, all familiar faces, showed up at our peaceful protest today. I am shocked to learn about the threat. That is serious and not something any of our protesters would do."Members of the group said Tea Party supporters and Minutemen also appeared at the rally, 10News learned.It was unclear, however, if any of those groups might have been involved in the threat.Issa, who is in Washington, D.C., issued the following statement regarding the incident, but before the device was ruled harmless:
"Shortly after 1 pm PST today, my district office received a phone call. During this call, a staff member was told that something had been left outside that would explode. My district office staff immediately contacted the San Diego County Sheriff's office and was thereafter evacuated from the office along with other occupants of the building. The phone call followed a protest at my district office of individuals associated with MoveOn.org and Occupy North County as well as individuals participating in a counter protest.I understand the San Diego County Sheriff's Office has determined that the item left behind does not pose an actual threat. All staff members who were working in the office today are safe and I understand no other individuals have been harmed in this incident.I deeply appreciate the efforts of those from the San Diego County Sheriff's office and the Vista Fire Department who responded to this incident. I will certainly assist them, as requested, as they continue their investigation of what happened and who is responsible."