Application. the wi-fi was bad and she did not use the school intercom. >> a good magnify a situation. >> reporter: that is the door the gunman used to enter the school. according to the report, the door was unlocked. had the door been locked, as the policy required, it would have slowed down the gunman. >> reporter: instead, surveillance video showed the gunmen walked into the building through an unlocked door. why was the door unlocked? >> i'm not sure. >> so, that there was normally locked during the day? >> always locked. >> reporter: always? >> yes. >> reporter: then, walk into a classroo...