He was allowed to enter the building. Spent the last 14 years of my career installing these secure entry doors and portals in schools across five states. There are NO provisions to allow keeping a door unlocked or holding it open. They are not considered fire exits and never have panic push bars. Many are electronic locksets with only a push/pull and unkeyed and often with additional mag-locks through bolted in the frame. Most were monitored triple security test controlled entry points. After entering the vestibule in a glass front facility you must gain security approval to be allowed to proceed. If approved you may be buzzed in to reception and continue with security checks. If you are a known non-threat (teacher returning to campus) you can be buzzed in directly to the corridor through the next set of impact resistant glass doors. Had the monitors exited the reception area through their reception counter side door, the assailant would have had to fire repeatedly into the corridor entry doors until the impact resistant glass failed. All this with armed cops on site? IMO this was allowed to occur.