(CNN) Law enforcement officials on the scene of the Uvalde, Texas, school shooting last month were aware there were injured individuals trapped inside classrooms before authorities decided to breach the entrance to the classrooms, according to a New York Times review of investigative documents and videos from law enforcement.
"People are going to ask why we're taking so long," a law enforcement official on the scene of the shooting could be heard saying, according to the Times, which cited a transcript of law enforcement body camera footage.
"We're trying to preserve the rest of the life," the transcript reads, according to the Times.
More than two weeks since the attack, questions remain about how the massacre unfolded and how police responded. Authorities have repeatedly changed their explanations of the events of May 24, frustrating the public and officials alike.
"We're ready to breach, but that door is locked," Pedro "Pete" Arredondo, the Uvalde school district police chief, said around 12:30 p.m., the Times reported, citing a transcript. Arredondo has been identified by authorities as the official who led the flawed law enforcement response to the shooting.
The Times reported that officers had grown impatient and were voicing their concerns.
"If there's kids in there, we need to go in there," one officer could be heard saying, according to the Times, which cited investigative documents.
"Whoever is in charge will determine that," another officer responded, according to the Times.
According to CNN's timeline of events, the first officers entered the school building at roughly 11:35 a.m. -- just moments after the 18-year-old gunman, who went on to kill 19 young students and two teachers that day.
By roughly 11:44 a.m., officers on the scene were calling for additional resources, equipment, body armor and negotiators and evacuating students and teachers, officials previously said.
By 12:03 p.m., there were "as many as 19 officers" gathered in the hallway of the school, while the gunman was inside the adjoining classrooms where the massacre took place.
At the same time, a student from inside one of the adjoining classrooms called 911 identifying herself and the classroom she was in, officials said. She called again at 12:13 p.m. and then again several minutes later, telling dispatchers there were eight to nine students still alive, according to authorities.
Law enforcement breached the classroom door at 12:50 p.m., using keys from a janitor, and shot and killed the suspect.
In a May 27 news conference, Department of Public Safety Director Steven McCraw said the classroom was not immediately breached because the incident commander -- Arredondo -- thought the scene was a "barricaded subject situation" and not an active shooter situation. He said the district police chief believed "there was time to retrieve the keys and wait for a tactical team with the equipment to go ahead and breach the door and take on the subject."
"From the benefit of hindsight where I'm sitting now, of course it was not the right decision," McCraw said at the time about the supervisor's call not to confront the shooter. "It was the wrong decision. Period. There's no excuse for that."
CNN has reached out to DPS and Uvalde County District Attorney Christina Mitchell Busbee's office for comment.
Attempting to get more answers about the tragedy, a Texas House investigative committee on Thursday held its first hearing in the mission and could produce a preliminary report by the end of the month.
A source close to the committee said that report is expected to focus on the facts only and include a chronological sequence of events, a timeline and details on the shooter. The committee is quasi-judicial and has subpoena power, and all witness testimony will be under oath, the source said.
The Texas Rangers, an investigative branch of the state's public safety department, are also investigating the massacre and the law enforcement response. The US Justice Department is also reviewing the law enforcement response at the request of Uvalde Mayor Don McLaughlin.
In a Thursday statement in response to the Times article, Texas Gov. Greg Abbott's press secretary Renae Eze said, "The investigations being conducted by the Texas Rangers and the FBI are ongoing, and we look forward to the full results being shared with the victims' families and the public, who deserve the full truth of what happened that tragic day."