Scene of Texas school shooting
Scene of Texas school shootingREUTERS/Marco Bello

The gunman behind the mass shooting at an elementary school in Texas this week lingered outside the building for 12 minutes firing shots, before walking into the school and barricading in a classroom where he killed 19 children and two teachers, authorities said in a news conference Thursday.

Victor Escalon, a regional director for the Texas Department of Public Safety (DPS), said, according to The Wall Street Journal, that he couldn’t say why no one stopped the gunman, 18-year-old Salvador Ramos, from entering the school during that time Tuesday.

Most of the shots Ramos fired came during the first several minutes when he entered the school, Escalon said.

DPS officials previously said an armed school officer confronted Ramos as he arrived at the school. Escalon said Thursday that information was incorrect and no one encountered Ramos as he arrived at the school.

“There was not an officer readily available and armed,” he was quoted as having said.

Ramos shot his grandmother Tuesday morning and then used her truck to drive to Robb Elementary School, crashing the truck into a nearby ditch at 11:28 a.m., according to the timeline laid out by Escalon.

The gunman then began shooting at people at a funeral home across the street, prompting a 911 call reporting a gunman at the school at 11:30. Ramos then climbed a fence onto school grounds and began firing before walking inside, unimpeded, at 11:40. The first police arrived on the scene at 11:44 and exchanged gunfire with Ramos, who barricaded himself in a fourth-grade classroom. There, he killed the students and teachers.

A Border Patrol tactical team went into the school an hour later, around 12:40, was able to get into the classroom and kill Ramos, Escalon said.

State officials have said that local police were at the school within a few minutes of the gunman entering the building and exchanged gunfire with him, but they were unable to gain access to a classroom where he barricaded himself, firing on officers.

Asked at the press conference why law enforcement weren’t able to respond in the initial 12 minutes Ramos was outside the school, Escalon said that was part of the investigation.

“Our job is to report the facts and have answers. We’re not there yet,” he said.

Texas Governor Greg Abbott said on Wednesday that the gunman revealed on Facebook just before the shooting that he was going to attack a school.

Abbott said the gunman wrote three messages on Facebook before the attack: once, about 30 minutes before the school shooting, to say he was going to shoot his grandmother, once to say he had shot his grandmother, and a third time — approximately 15 minutes before the shooting — to say he was going to open fire at an elementary school.

Facebook said the posts "were private one-to-one text messages that were discovered after the terrible tragedy occurred," and that the company is "closely cooperating with law enforcement."