This story is part of a KXAN series of reports called “Stop Mass Shootings,” providing context and exploring solutions surrounding gun violence in the wake of the deadly Uvalde school shooting. We want our reports to be a resource for Texans, as well as for lawmakers who are convening a month after the events in Uvalde to discuss how the state should move forward. Explore all “Stop Mass Shootings” stories by clicking here.

AUSTIN (Nexstar) — The state’s top law enforcement official revealed devastating new details about police response to the Uvalde school shooting, in testimony to a Texas Senate committee on Tuesday.

Texas DPS Director Col. Steven McCraw publicly laid out the most extensive timeline yet of what happened on May 24, when an 18-year-old gunman was left alone in conjoining classrooms for more than an hour, killing 19 children and two teachers.

McCraw revealed that there were enough armed officers on the scene to stop the gunman, as soon as three minutes after he entered the building. He also told lawmakers there was no evidence showing that officers on scene attempted to unlock the classroom door where the gunman was inside.

“I have great reasons to believe it [the classroom door] was never secured,” McCraw said, after revealing the teacher had previously reported her door lock was malfunctioning, before the shooting.

Instead, armed officers with rifles waited in the hallway for more than an hour before eventually breaking into the classroom and killing the gunman. McCraw placed the blame squarely on Uvalde CISD Police Chief Pete Arredondo, who he described as the scene’s “incident commander.”

“The only thing stopping a hallway of dedicated officers from any room 111 And 112 was the on-scene commander who decided to place the lives of officers before the lives of children,” the director testified.

Law enforcement has been scrutinized in the aftermath of the shooting for their delayed response in breaching the classroom and killing the gunman.

“There’s compelling evidence that the law enforcement response to the attack at Robb Elementary was an abject failure and antithetical to everything we’ve learned over the last two decades since the Columbine massacre,” McCraw said.

Lt. Gov. Dan Patrick wrote on Twitter Tuesday, “the TX Senate begins public hearings on latest DPS investigations on Uvalde & other topics. The Senate believes all testimony should be in the open. The families & the public have a right to know.”

Earlier this month, Gov. Greg Abbott called for the creation of special committees to address school safety and mental health after the tragedy.

The House Investigative Committee into the shooting also met Tuesday morning — and was again closed to the public. The three-member panel heard from responding law enforcement in the shooting. Arredondo, who has been largely silent since the shooting, testified to that House committee.

Arredondo took no questions from reporters following his testimony as he was ushered to an elevator, escorted by a DPS trooper.

Meanwhile, furious senators expressed frustration with the information they learned from McCraw about Arredondo’s handling and response.

“I challenge this chief to come testify in public to testify as to what happened here,” Sen. Paul Bettencourt, R-Houston, said. “Don’t go hiding in the House. Come to the Senate where the public of Texas can ask these questions.”

Last month, McCraw called waiting to breach the classroom “the wrong decision,” and now some parents in the Uvalde school system want Arredondo fired.

In an interview with the Texas Tribune, Arredondo defended his response during the shooting, saying, “not a single responding officer ever hesitated, even for a moment, to put themselves at risk to save the children. We responded to the information that we had and had to adjust to whatever we faced.”

Tuesday’s Senate hearing lasted more than 12 hours with lawmakers also questioning top education and law enforcement officials including Texas Education Agency Commissioner Mike Morath, and John Curnutt, Assistant Director of the Advanced Law Enforcement Rapid Response Training (ALERRT) Center at Texas State University.

Curnutt told senators ALERRT — which is internationally renowned for its law enforcement active shooter training — was putting together its own review of what happened in Uvalde.

On Monday, Democratic members of the Texas Senate called for approval of four gun safety measures in the wake of the shooting. The group would like to raise the minimum age to buy certain guns to 21, require background checks, a 72-hour waiting period for specific weapons and red flag laws. 

Republicans have largely resisted calls for tighter gun restrictions, arguing it won’t prevent another mass shooting from happening and pointing to mental health and school safety solutions.