A loaded gun was discovered by a cleaning person inside a secure area at the Tucson International Airport on Thursday. The Transportation Security Administration (TSA) ordered the west wing of the airport to be evacuated after the security breach was discovered. The gun, found in a bathroom trashcan, had apparently made its way past multiple levels of security, including a federal TSA checkpoint. 

So, how did a loaded gun get through a metal detector? Thus far, TSA has offered no comment