AUSTIN (Nexstar) — More than two weeks after the second deadliest school shooting in U.S. history, Texas lawmakers kicked off an investigation into what happened behind closed doors Thursday.

The three-panel investigative committee met with witnesses and heard testimony in an hourslong hearing not open to the public. Chairman Rep. Dustin Burrows, R-Lubbock, said in a statement last week that their goal is to provide an “unbiased and objective report” to help inform the legislature in policy to help prevent future school shootings.

The investigation comes amid growing criticism from state leaders, experts and the community over how Uvalde law enforcement responded to the active shooter threat. Police took more than an hour to enter the classroom, where the shooter opened fire with an AR-15 rifle, killing 19 children and two teachers.

“In an effort to want to be thorough, and more importantly accurate, we’re going to continue to review this as a committee, individually, [and] make sure that we continue to visit with more individuals who have firsthand accounts before we reveal more information or any conclusions,” Burrows said during the public portion at the end of Thursday’s hearing.

Burrows, who is also an attorney, said they were briefed by the Texas Department of Public Safety, including its director Col. Steven McCraw, and began looking at the physical evidence.

The chairman also acknowledged the need for transparency but said committee members want to “respect the process” and ensure all the facts are correct first.

“We are just now beginning to see and talk about things. I don’t want to be more part of the problem by giving a real-time accounting until we can be accurate and make sure that we have a full representation of what it is,” he told reporters.

Texas Speaker of the House Dade Phelan announced the creation of this three-person investigative committee Friday. The committee will have subpoena power. Rep. Joe Moody, D-El Paso, is serving as the vice-chair. Former Texas Supreme Court Justice Eva Guzman, who recently ran to be the Republican nominee for state attorney general, will also be a member of the panel.

“The fact we still do not have an accurate picture of what exactly happened in Uvalde is an outrage,” Phelan said in a statement. “Every day, we receive new information that conflicts with previous reports, making it not only difficult for authorities to figure out next steps but for the grieving families of the victims to receive closure.”

The Department of Justice and the Texas Rangers are also running investigations into law enforcement’s response.

Burrows said he does not know when the investigation will be complete but said the committee “may produce a preliminary report” for the public before the investigation’s conclusion. He said no decisions were made during Thursday’s hearing.