News reports are saying the murderer got access to the school through an unlocked outside access door to an empty half of a classroom area. The classroom area being divided in half by a folding screen (prob’ly attached to the ceiling) that could be slid away to use the whole area at once.
That access door may have been unlocked/propped open for convenience or may have simply failed to close properly the last time it was opened (custodians usually check that access doors are locked at the end of the day).
Several hundred kids in that school, the murder confined to one classroom. The emergency school lockdown procedures (cleared hallways, locked doors, no inside windows) may have otherwise worked well.
"...if the gentlemen of Virginia shall send us a dozen of their sons, we would take great care in their education, instruct them in all we know, and make men of them." Canasatego 1744
