The Texas school shooter was able to barricade himself in a classroom despite the district's security plan including police officers and locked doors

• The Texas school shooter was able to barricade himself inside of Robb Elementary for nearly an hour despite the district's comprehensive security plan.
• The plan includes police and security officers on campus and instructs teachers to keep doors locked at all times.

A gunman who fatally shot 19 children and two adults at Robb Elementary School in Uvalde, Texas, earlier this week was able to barricade himself into a classroom despite the district's comprehensive security plan that includes employing police officers, monitoring social media, and locking doors.

According to the Uvalde Consolidated Independent School District's preventative security measures, the 21-point plan is in place to address and eliminate "problems of violence, vandalism, disruptions, and fear" in its classrooms.

The plan says that the UCISD employs four police officers — a chief, a detective, and two officers. There is also supposed to be security staff on "secondary campuses," the plan says, who "patrol door entrances, parking lots and perimeters of the campuses."

The plan says that Robb and other elementary schools are fenced in to limit who has access to the campus. District schools also have security vestibules with outside door buzz-in systems at their front doors, the plan says.

The plan also says that staff and students are regularly trained on what to do when there is a threat on campus, and teachers are "instructed to keep their classroom doors closed and locked at all times."

Additionally, UCISD says in its security plan that it monitors social media posts with connections to the district to investigate possible threats against students or staff.

The gunman reportedly wrote in Facebook messages saying that he was going to attack an elementary school, just after posting that he had shot his grandmother. Facebook's parent company Meta said these messages were private, meaning the district wouldn't see them.

Ultimately, the gunman was still able to enter a classroom, where he fatally shot young children and their teachers.

Texas Department of Public Safety Director Steve McCraw said this week that an Uvalde Consolidated Independent School District resource officer approached the gunman outside the school, but the shooter was still able to make it inside the building.

McCraw said the gunman entered Robb Elementary through a back door, so he did not face the security measures implemented at the school's front doors.

Once inside the building, the gunman "went down a hallway, turned right, then turned left," where he encountered two adjoining classrooms, McCraw said.

It remains unclear how he entered the classroom — or if it was locked when he arrived.

McCraw said the gunman was inside the school for 40 minutes before authorities breached the classroom door and shot and killed him.