A grand jury in Uvalde will investigate the response to the school massacre

The district attorney in Uvalde, Texas, has said for months that she planned to convene a grand jury to consider evidence from the 2022 Robb Elementary School shooting, with the possibility that criminal charges could result from the botched police response to the massacre.

The district attorney, Christina Mitchell, said in an email in December that she would “dissect the Texas Rangers investigation” into the shooting “and then present it to a Uvalde County grand jury for review.”

It emerged on Friday that selection for the grand jury had begun, according to a person with knowledge of the matter. The investigation would likely take months.

Word that the grand jury had been convened, first reported by Uvalde's news leadercame a day after the Justice Department released a 600-page report that found broad and “unimaginable” failures that delayed the response and subsequent medical care to victims after the mass shooting.

Ms. Mitchell's investigation had been anticipated by relatives of the shooting victims and survivors, who have long said that a near-total breakdown of police protocols by about 370 police officers could have worsened the outcome of a shooting. 19 children and two teachers dead.

The grand jury could be asked to determine whether any of the officers broke the law by waiting 77 minutes to confront the teenage gunman, who holed up in two connected classrooms while some children from one of the classrooms called 911 for help .

Although police officers have occasionally been charged and convicted for their actions during deadly encounters, criminal charges against police officers who failed to protect the public remain rare. According to police experts, the law generally does not require people to put themselves in harm's way, even if training instructs them to do so.

Ms. Mitchell did not respond to a request for comment Friday.

Twelve jurors had been selected to serve on the grand jury on Friday, according to the person familiar with the case; they were expected to hear evidence in the coming days.

Two months before the massacre, Uvalde School District Police Department officers had completed active shooter training, including guidelines calling for them to immediately confront a gunman to prevent more bloodshed. “A first responder who is unwilling to put the lives of innocents ahead of their own safety should consider another career field,” the guidelines say.

Some of the first officers on the scene initially walked toward the door leading to one of the classrooms where the gunman had opened fire, but they were fired upon. That's when they were captured on camera waiting outside in the hallway. The local school's police chief had classified the incident as a barricaded subject rather than an active shooter situation, which would have called for a more aggressive approach.

Federal border agents eventually confronted the gunman and killed him.

At a media briefing Thursday in Uvalde, U.S. Attorney General Merrick Garland said “lives would have been saved and people would have survived” if officers had acted more quickly to confront the gunman.

Mr. Garland said the protocols call for responding officers to “immediately enter the room to restrain the shooter using whatever weapons and tools the officers have.”

Blame for the delayed police confrontation with the shooter has shifted since the day of the shooting. Shortly after the tragedy, top state police official Steven McCraw pointed the finger at local school police chief Pete Arredondo. It then emerged that state police officers were also among those who failed to actively confront the shooter. In its report, the Justice Department focused largely on Mr. Arredondo's decisions, finding that his decisions delayed the response.

Mr. Arredondo, who says he has become a “sacrificial lamb” in the situation, has said he acted to save as many lives as possible, including those of students in nearby classrooms who may have been injured by crossfire.

J. David Goodman contributed reporting from Houston.