Originally Published: 18 JAN 24 01:43 ET

Updated: 18 JAN 24 09:51 ET

By Ashley Killough, Shimon Prokupecz, Carolyn Sung and Elizabeth Wolfe, CNN

(CNN) — [Breaking news update, published at 9:51 a.m. ET]

Critical failures in leadership among specific law enforcement officers who rushed to the mass shooting at Robb Elementary in Uvalde are blamed by the Justice Department, in a new 575-page report being made public nearly 20 months after the massacre that left 19 students and two teachers dead.

It’s the fullest official accounting of what happened, though much already was known largely through CNN investigation.

CNN obtained a copy of the report from a family member of a Robb Elementary student. The full report is expected to be released publicly Thursday afternoon.

“The response to the May 24, 2022, mass casualty incident at Robb Elementary School was a failure,” the Justice Department report concludes bluntly.

The report chronicles the quick arrival of law enforcement officers who ran toward the sound of gunfire, then almost immediately stopped once they got near the classrooms where the gunman was killing fourth graders and educators.

It took 77 minutes from when the 18-year-old shooter walked into Robb Elementary School until he was stopped.

“Officers on scene should have recognized the incident as an active shooter scenario and moved and pushed forward immediately and continuously toward the threat until the room was entered, and the threat was eliminated.

That did not occur,” it says.

Instead, the intensity level dropped as responders began to treat the situation as a “barricaded suspect” operation that did not need immediate action, even as more officers arrived and the signals of ongoing danger multiplied.

That was the “single most critical tactical failure,” the team from the Justice Department’s Office of Community Oriented Policing Services finds.

[Previous story, published at 9:03 a.m. ET]

The US Justice Department is expected to release the findings of its probe into law enforcement’s widely criticized response to the 2022 Uvalde school massacre on Thursday, a day after US Attorney General Merrick Garland met with victims’ families in Texas to brief them on its content.

The report’s release comes nearly 20 months after the shooting at Robb Elementary School, in which 19 children and two teachers were killed, as the community continues to wonder why it took more than 370 law enforcement officers on scene more than 77 minutes to stop the gunman.

Alfred Garza III, whose 10-year-old daughter Amerie Jo Garza was among those killed, told reporters the meeting “went OK,” and he hoped the report might “answer some of the questions that we didn’t know.”

“We had a lot of questions asked in there and I think they’re really going to give us a lot of insight (in the report) on some of the stuff we maybe didn’t know,” he added. Garza said he did get some of his own questions answered Wednesday, but didn’t want to get into specifics ahead of the report’s release.

Relatives were not provided a copy of the report during the meeting.

Still, the families yearn for “accountability,” Garza said.

“That’s what everybody wants, that’s what we all want,” he said. “We want people to be held accountable for what they didn’t do that day. That’s all that’s left to do.”

The DOJ said its goal in releasing its critical incident review Thursday is “to provide an independent account of law enforcement actions and responses; identify lessons learned and best practices to help first responders prepare for and respond to active shooter events; and provide a roadmap for community safety and engagement before, during, and after such incidents.”

The parents of victim Khloie Torres left the meeting early, after about an hour. Ruben and Jamie Torres expressed disappointment, telling CNN they essentially didn’t hear anything new.

Khloie, who survived the May 24 massacre, was 10 years old when she was trapped inside Robb Elementary School with the gunman who slaughtered her friends and teacher while holed up in two adjoining classrooms. She made repeated calls to 911 throughout the incident.

The botched response went counter to a widely taught protocol for active shooter situations that calls for police to immediately stop the threat. And frustration and criticism built in the months after the shooting – exacerbated by the fact that some authorities gave contradicting narratives about how the response unfolded.

A preliminary Texas House investigative committee report released in July 2022 found “systemic failures and egregious poor decision making” by several law enforcement agencies.

Oscar Orona, whose son Noah survived the massacre after being shot in the back, said he’s hopeful the report will illustrate authorities’ “abysmal failure” to the public.

“We look forward to seeing the report because I think it will validate a lot of our feelings already as to what transpired and what should have happened,” the father told reporters after the Wednesday meeting.

Once the report is released, the “next step is to find out what will be done with this information,” Amerie Jo’s grandmother, Berlinda Arreola, told CNN.

Families were not given many specific details about the report’s contents, but they were told it was a “very thorough investigation,” said Brett Cross, the legal guardian of Uziyah Garcia, who was killed.

“We still have to process it emotionally, and hopefully this will bring some changes and some accountability that we’ve been fighting and asking for since the very beginning,” he said.

Conflicting stories and lingering questions

Officers from 23 agencies, including the US Border Patrol, the Texas Department of Public Safety and the local police department, participated in the response and officials have given conflicting narratives about what happened that day.

Law enforcement experts and victims’ families have questioned whether lives could have been saved if authorities had acted sooner.

Surveillance video of officers waiting in the school’s hallway while the gunman roamed the two classrooms with dead and injured children inside raised questions about the response. Some slain victims were still alive in the time it took officers to breach the classrooms and kill the gunman.

There has also been confusion about exactly who was in charge at the scene. Some investigators said it should have been former Uvalde Consolidated Independent School District Police Chief Pedro “Pete” Arredondo, though Arredondo has said he did not consider himself to be the incident commander.

Arredondo was fired three months after the shooting.

The more than 90 officers from the Texas Department of Safety who were on scene have also faced scrutiny.

Seven DPS officers were investigated for their responses, the agency told CNN last year. Two were “served with employment discharge notifications, one was served with a formal written reprimand and the remaining four were closed without sustained findings,” the agency said.

Uvalde County District Attorney Christina Mitchell previously said she will charge law enforcement officers in relation to the response if warranted. She has said the criminal investigation could take years.

This is a developing story and will be updated.

CNN’s Holly Yan, Hannah Rabinowitz, Melissa Alonso and Holmes Lybrand contributed to this report.

The-CNN-Wire