Noted.In this case "Barricaded" means he lock himself inside the class and LE was unable to break down the door.
Using a key to unlock a door, to me, does not constitue a "barricade" that denies reasonable access. I call it... a "door" with easy access by any number of readily availalble keys and number of personnel.It is my understanding LE had to use a staff members key to gain entry.
I don't know though. Maybe there where cabinets or desks in the classroom he used to reinforce the door and deny entry, but wasn't mentioned once entry was finally gained. An ommission of facts is possible at this point.