These problems are not new to the World Trade Center incident ; cross-department and cross-discipline communication has been a hotly contested and long-identified issue . For example , at the Oklahoma City federal building bombing incident , the inability to communicate among departments was also cited as a problem . Firefighters heard an evacuation order on their radio channel because of the reported presence of a second bomb . Police and EMS workers reportedly did not know of the order
Oklahoma City federal building bombing incident
Oklahoma City bombing
Communication during the September 11 attacks