NEW : An Air Force official says no gunman was found and the site is `` secure '' The lock down was initiated hours earlier after `` unconfirmed sightings '' of an armed man . He added that the building , where the gunman was once thought to have entered , has been secured after authorities went through it room-by-room . FBI agents , along with Tucson police , were dispatched to the Arizona air base to help . A perimeter has been set up around the building where a suspect may be hiding inside.
NEW : An Air Force official says no gunman was found and the site is `` secure '' The lock down was initiated hours earlier after `` unconfirmed sightings '' of an armed man . FBI agents , along with Tucson police , were dispatched to the Arizona air base to help . A perimeter has been set up around the building where a suspect may be hiding inside.