(UVALDE, Texas) -- Two months before Tuesday's mass shooting in Uvalde, Texas, that left 19 children and two adults dead, the Uvalde school district hosted an all-day training session for local police and other school-based law enforcement officers focused on "active shooter response."
"First responders to the active shooter scene will usually be required to place themselves in harm's way," according to a lengthy course description posted online by the Texas agency that developed the training. "Time is the number-one enemy during active shooter response. ... The best hope that innocent victims have is that officers immediately move into action to isolate, distract or neutralize the threat, even if that means one officer acting alone."
Now relatives of victims and neighbors of Uvalde's Robb Elementary School are raising questions over how police officers who first arrived on the scene handled the situation -- including whether they followed their own training.
At a press conference on Friday, Texas Department of Public Safety Director Steven McCraw acknowledged that officers on the scene miscalculated what was unfolding, failing to go after the gunman sooner.
"From the benefit of hindsight where I'm sitting now, of course it wasn't the right decision. It was the wrong decision, period," he said.
On Tuesday, a spokesperson for the DPS, Lt. Chris Olivarez, said on national TV that at one point on Tuesday, police officers on the scene decided to "focus" on evacuating students and teachers "around the school," instead of racing to the shooter's location -- even as they heard more gunshots.
"They kept hearing the gunfire as they were doing this, as they were performing these rescues," Olivarez said Wednesday on CBS.
ABC News contributor John Cohen, formerly the top counterterrorism official at the U.S. Department of Homeland Security and himself a former police officer, said that response "would seem to be inconsistent with accepted practice."
"What we are hearing from Texas law enforcement officials seems to be inconsistent with the operational philosophy that has guided the response to active shooter situations for well over a decade," Cohen said. "Having been a police officer, it's a scary job -- but what the public expects is that when confronted with those situations, the officer is going to do what they need to do in order to protect the public."
A man who lives across the street from Robb Elementary School, Jesse Ortiz, told ABC News that he watched on Tuesday as officers took cover behind a vehicle.
"I said, 'Why aren't you going inside? Why aren't you going inside?'" he recalled.
Videos posted online show angry parents outside the school, urging police officers to take more action.
In the wake of the 1999 high school shooting in Columbine, Colorado, where 12 students and one teacher were killed, federal and state law enforcement officials developed new practices for equipping and training first responders. As a result, Cohen said, it has become "generally accepted" that the first officers on-scene must find and "engage" the shooter as soon as possible, even if that means putting their own lives at risk.
In 2019, the International Association of Chiefs of Police's policy center published an "issues paper" on active-shooter situations, which noted that "current thinking reemphasizes that, given proper justification as defined by law and agency policy, taking immediate action during active shooter incidents, rather than waiting for specially equipped and trained officers, can save lives and prevent serious injuries."
"[I]t has been recognized that even one or two armed officers can make a difference in the outcome of active shootings by taking swift, but calculated, individual or coordinated action," the paper said. "Time lost by delayed action is likely to result in additional casualties."
Over the past decade, law enforcement officers in cities and states across the country have received training reflecting such policies, according to Cohen. The course that the Uvalde school district hosted in March was developed by the Texas Commission on Law Enforcement, which oversees the certification of police officers throughout the state and requires school-based officers to take the "active shooter response" course.
On Thursday, a top Texas Department of Public Safety official held a press conference seeking to clarify what unfolded two days earlier -- though he didn't answer some key questions.
Victor Escalon, director of the DPS South Texas Region, told reporters that about four minutes after the shooter first entered the school, "initial officers" on scene "receive[d] gunfire" and "[didn't] make entry initially because of the gunfire." At that point, officers call for "additional resources," including tactical teams, body armor, and other equipment, and they also begin evacuating students and teachers, Escalon said.
It was "a complex situation" with "a lot going on," Escalon said. About an hour after the shooter first opened fire inside the school, a tactical team from the U.S. Border Patrol arrived, entered the school with other law enforcement, and then killed the shooter, according to Escalon.
Toward the end of the press conference, a reporter asked Escalon, "Did you follow best practices for active shooter scenarios?"
Escalon didn't answer, instead telling reporters, "I have taken all your questions into consideration ... we will answer those questions."
In 2014, the FBI released a study of 160 active shooter incidents that had occurred since 2000. It highlighted "the damage that can occur in a matter of minutes," noting that the vast majority of active shooter incidents ended in five minutes or less -- and more than a third of those whose durations could be ascertained ended in two minutes or less.
"Officers need to operate in a way that not only protects their safety, because a dead officer is not going to [help], but at the same time, the absolute number-one priority for a law enforcement officer responding to the scene is to ... prevent people from being killed or injured," Cohen said.
"That's why they're there," said Cohen. "That's why they took the oath."