"A teacher had propped open the door at 11:27 a.m. — a minute before Ramos crashed the truck into a ditch near the campus."
"Ramos popped out of the passenger side door of the truck brandishing a long rifle and carrying a bag of ammo, then fired shots at two men at a funeral home nearby. The teacher ran into the building to get her phone and came back outside, but left the door propped open, McGraw said."
"She made a 911 call at 11:30 a.m. while Ramos walked across the parking lot and opened fire on the school building authorities said."
https://nypost.com/2022/05/27/texas-school-shooter-got-in-through-door-propped-open-by-teacher/