The director of the Department of Public Safety said that police officers wasted time looking for a classroom door key that was “never needed.”.

AUSTIN, Texas — The head of the Texas State Police on Tuesday offered a pointed and emphatic rebuke of the police response to a shooting last month at Robb Elementary School in Uvalde, Texas, calling it “an abject failure” that ran counter to decades of training.

In his comments before a special State Senate committee in Austin, Steven McCraw, the director of the Department of Public Safety, provided the most complete public account yet of his agency’s month-old investigation and a forceful argument that officers at the scene could have — and should have — confronted the gunman without delay after arriving.

Just minutes after a gunman began shooting children on May 24, he said, the officers at the scene had enough firepower and protective equipment to storm into the classrooms.

McCraw’s testimony addressed a central, and painful, question that still hung over the massacre and the delayed police response, one that investigators have attempted to answer through interviews with officers and reviews of video: Were the doors to the classrooms locked, preventing police officers from entering in time to save others.

McCraw focused his blame on the on-scene commander, whom he identified as the chief of the Uvalde school district’s Police Department, Pete Arredondo, who he said was the highest-ranking person at the scene.

Bettencourt said loudly at one point, referring to Chief Arredondo.

A lawyer for Chief Arredondo did not respond to a request for comment, and the chief, who recently was seated as a member of the Uvalde City Council, has said he does not want to discuss the case further until the investigation has been completed.

At a City Council meeting on Tuesday evening, Uvalde’s mayor, Don McLaughlin, called the legislative hearing a “Bozo the Clown show” and “a farce” that placed blame on the Uvalde school district police but did not address the role of officers from the Department of Public Safety and several other agencies who were also on scene.

The Council voted on Tuesday not to offer a leave of absence to Chief Arredondo, who has not attended Council meetings since he was sworn in not long after the shooting.

McCraw in Austin, which lasted more than four hours, was unusually charged because it followed weeks of little to no official updates on the investigation and came after what had been a halting and troubled initial effort by top state officials to provide details about the shooting and the police response.

McCraw has been the director of the Department of Public Safety since 2009 and oversees both the State Police and the Texas Rangers, the organization conducting the investigation into the Uvalde shooting.

McCraw brought poster boards showing a timeline of the shooting and police response at the school, photos of doors at the school, and two maps depicting how the gunman and police officers entered the school and then the two connected classrooms.

The senators asked direct questions about the response, but also addressed the broader political debates over school safety and gun regulation that have erupted in the wake of the shooting in Uvalde.

McCraw confirmed details first reported by The New York Times over a series of articles during the past month, including that the officers who first made it inside the school — two minutes after the gunman — had AR-15-style rifles, and that shields that could have been used to protect officers making an entry into the classroom had arrived before 12 p.m., nearly an hour before officers finally went in.

McCraw also presented new details, such as the exact time that Chief Arredondo went into the school, at 11:36 a.m., three minutes after the gunman entered the classrooms and began firing.

The timeline also noted that, by 11:54 a.m., a Texas Ranger was inside the school, one of at least 12 members of the State Police who responded between the time when the gunman began shooting in classrooms at 11:33 a.m.

The information that had to be corrected included the length of time it took for officers to fire the first shots at the gunman (not immediately, but one hour and 17 minutes after he began shooting inside the school) and how he had gained access to the building (not through a door that had been propped open, but through one that was unlocked).

The shifting narrative surrounding the massacre, which left 19 children and two teachers dead, quickly undermined trust in the official accounts of the shooting and created tension between state officials and those in Uvalde, most of whom rallied around their city Police Department and Chief Arredondo.

McCraw held a news conference three days after the shooting and said that Chief Arredondo had been in charge of the police response and had made the “wrong decision” in not trying to immediately confront the gunman.

The Times revealed that police supervisors had been told there were people alive but wounded in the classrooms; that an officer had been on the phone with his wife, a teacher, after she was shot but before she died, and that he had told other officers about this at 11:48 a.m., providing them with a clear indication that people inside the classrooms were in urgent need of help; and that a Uvalde police officer passed up an opportunity to take a shot at the gunman outside the school, fearing he might hit children.