We now know what's causing the traffic nightmare in and around Coronado stemming from police activity at the Naval Air Station North Island.  Naval Base Coronado Public Affairs Officer Sandy Demunnik tells KOGO News that a bomb threat was reported to the main gate around 5:00 Thursday morning. 

The base's main gate on 3rd and Alameda Boulevard has been shut down.  Cars are being diverted to the gate on 1st and Alameda or the gate on Ocean boulevard.  

Navy officials are investigating the credibility of the threat, and they're also waiting for a explosive ordinance disposal team.  The Navy asks that all sailors and civilians working at North Island call into their command before heading into work.