Uvalde Consolidated Independent School District had doubled its security budget in recent years, according to public documents, in part to comply with state legislation passed in the wake of a 2018 school shooting in which eight students and two teachers were killed. The district adopted an array of security measures that included its own police force, threat assessment teams at each school, a threat reporting system, social media monitoring software, fences around schools and a requirement that teachers lock their classroom doors, according to the security plan posted on the district’s website…

Somehow — the account provided by authorities is not entirely clear — a high school dropout with no known criminal history was able to evade a district officer outside Robb Elementary School on Tuesday and enter a back door armed with a rifle. From there the gunman, 18, proceeded down a hallway and into a classroom, where he locked the door and opened fire, authorities said. Nineteen children were killed, along with two teachers. Police and federal agents soon arrived and got a school official to unlock the door, then shot the gunman dead, state and federal law enforcement officials said.