There are the typical self locking doors at our church. Let me explain how they work. I need a key to open the door from the outside. When the door shuts it auto locks, but from the inside, there is a bar you can push that will open the door. You can either prop the door open with something, or you can use the little Allen-wrench-looking device that is on a hook up at the top of the door on the inside, insert it in hole in the bar and turn. That will disable the auto lock.
So to be fair to the teacher….. what if she knew that the doors were never left unlocked, she might not have even known about the little device, so she used the rock to prop door open, then ran back inside, kicked the rock away, and assumed the doors locked when they closed. From the inside she would not be able to test the door to see if it locked . So someone else could have used the device earlier and disabled the auto lock.
Thank you for your explanation.. Doors with an interior push bar are supposed to lock when pushed shut. She would have no way of testing the door to see if it was locked after she moved the rock unless she tested it from the outside.
Unless it didn’t close all the way and latch. Or it was broken.
The shooter may have gone to that specific door because he saw the teacher run inside that door.
You have identified one of the greatest weaknesses of this design. In addition to not being able to tell if the door is really locked, I do not know if there is any way to electronically monitor if the autolock is activated. (I am not a door lock wizard, but am quite familiar with the standard system you describe.)
My guess is that practically every school in the country has that auto locking system and are susceptible to walk-ins.