As of 12:03 p.m. Tuesday, 19 police officers were standing in a hallway at Robb Elementary School.
In front of the door of the two connected classrooms, in which an 18-year-old gunman had been holed up for almost half an hour.
But officers were waiting for a squad and equipment, Texas Public Safety Agency director Steven McCraw said Friday.
Finally, at 12:50 p.m., the special unit opened the locked door with a key from the janitor and shot the attacker.
Meanwhile, students in that same classroom had dialed 911 ten times.
Two girls who were trapped with the gunman called repeatedly - four times each - asking for help.
When an emergency call was made at 12:21 p.m., shots were heard, according to the officer.
Sofia Dreisbach
North American political correspondent based in Washington.
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What McCraw said in a press conference on Friday afternoon about the course of events revealed the serious failings of the police in the killing spree in Uvalde, in which a young man shot 19 elementary school students and two teachers.
Then on Sunday, a spokesman for the US Department of Justice announced that an investigation into the police operation would be launched “at the request of the mayor of Uvalde”.
According to McCraw, the responsible officer in Uvalde had decided that the situation had changed - that the perpetrator was no longer shooting but had barricaded himself in.
He therefore assumed that "it is time and no other children are in danger" - according to McCraw, a misjudgment of the situation.
When a storm of shouts and indignant inquiries broke out after this announcement, McCraw asked for calm: In retrospect, "of course not" was not the right decision.
"It was a wrong decision.
There is no excuse for that.
Point.
We think that you should have stormed as soon as possible.” That is the “doctrine”: Each officer “finds the place where the bullets were fired and shoots until the person is dead”.
The man who made these miscalculations is the school district police chief, Pedro Arredondo.
According to the school district, he has been a police officer for almost thirty years.
Arredondo himself has not spoken publicly for two brief press conferences on the day of the rampage.
His decisions run counter to emergency responder protocol that has been widely in place since the 1999 Columbine High School shooting in Colorado.
At that time, two assassins killed twelve students and one teacher.
Since then, the aim has been to stop the shooter as quickly as possible – for example, even the care of the injured should be postponed.
A Department of Homeland Security document on how to deal with shootings states: “The aim of the police is to stop the shooting man as quickly as possible.
The apparent omission may be one reason why, in the days immediately following Tuesday's shooting, there was initially no concrete information about what had happened between the time the perpetrator arrived at the school and the special forces stormed it.
Statements from relatives who made serious allegations that the police intervened too late attracted attention on Thursday.
In a press conference on Thursday, an official from the Public Safety Agency then corrected another misinformation: Contrary to what was originally claimed, there was no armed security officer at the school who had tried to stop the perpetrator.
But he didn't give any details about the process.