A gunman killed 19 children and two teachers at an elementary school in Uvalde, Texas, on May 24, 2022, in what became one of the deadliest school shootings in U.S. history.

Inside the Uvalde Response, a new documentary from FRONTLINE, The Texas Tribune and ProPublica, draws on a trove of raw materials from a state investigation and pieces together the firsthand accounts of police officers who responded to the shooting to paint a picture of what it was like inside Robb Elementary School that day.

Using those investigative files — which, more than a year and a half later, have not been released to the public — the documentary probes the chaotic response and why it took the police 77 minutes to stop the gunman. Inside the Uvalde Response was written and directed by Juanita Ceballos, and produced by Ceballos and Michelle Mizner.

Ceballos and reporter Lomi Kriel spoke with FRONTLINE about how they sorted through hundreds of hours of body camera footage and investigative interviews in order to build the narrative shown in the documentary, the challenges of reporting on such a traumatic incident, and the lessons learned from the events of that day.

This interview has been edited for length and clarity.

Can you tell me how this investigation began?

Lomi: I’m a reporter with ProPublica and The Texas Tribune. I’m based in Texas. And so ever since the Robb School shooting, I have been covering this, along with my colleagues. In the course of reporting about this, we obtained a massive trove of investigative material that includes more than two dozen body cameras, more than 150 interviews with law enforcement officers, teachers, students, other people that were involved in the response that day, 911 calls, call logs. We did several stories related to that earlier this year and last year, and then we decided to team up with FRONTLINE to cohesively put together an insider look at how the response that day happened. FRONTLINE analyzed a lot of this material alongside us, and then we did additional reporting to look at not only what happened that day, how some of this could have gone so wrong; but also what it is we can learn from that going forward.

Juanita: I think obviously for the film, the focus was visual. So we started putting more focus on the body cameras. When I first joined, Lomi and the team had prepared a lot of documents and they had already transcribed most of the body cameras. I think the process then became more about: What are we seeing? And are there more body cameras that we can use to show one particular moment? And also, what are the key moments? How can we tell the story visually and help people understand what that hallway was like and what officers were thinking and mostly doing?

Can you share anything about the state-led investigation into the response? Do we know the status?

Lomi: After the shooting, there was a lot of confusing information that basically resulted in the Texas Rangers, which is part of the state police, conducting an investigation. The Justice Department is conducting a review of this. In addition to that, the Uvalde County district attorney is still conducting a criminal investigation into if there were any crimes committed that day. That’s part of the reason why we think that both the documentary and story are really important, because it really helps people to understand a little bit more about what happened that day when we really have almost no answers still — because none of those findings have been publicly released at all.

Read more: Why We’re Publishing Never-Reported Details of the Uvalde School Shooting Before State Investigators

What was your process for organizing all this material and piecing it together to create the minute-by-minute timeline that we see in the documentary?

Juanita: In terms of the process, what it meant was watching every single piece of bodycam footage and using software to transcribe what we were seeing. And also the timecode that’s on a lot of these body cameras doesn’t really match; it’s not the right time of day. So part of the work was trying to use moments throughout the response, for example, gunshots or moments in the radio logs that we could use to figure out what time we were watching, and transcribing everything from beginning to end. Once we were done doing that, we started putting together a timeline. And after we had that timeline and knew exactly where we could watch a certain moment or hear a certain piece of audio, then it was looking at: What are the key moments that will help people understand what happened?

Lomi: I would just emphasize both the huge amount of material that we went through — body cameras and interviews — listening to so many interviews with officers from so many agencies, as well as parents, children, teachers, and then trying to verify, in many cases, those accounts with them. We all tried to reach out to many of the officers that are identified in both the story and the film. Unfortunately, none of them agreed to participate, in part citing the ongoing investigations.

What were some obstacles you faced in the reporting and filmmaking process? How did you overcome them?

Lomi: I think this is inherently such a difficult topic. It’s such an emotional topic. It’s devastating to watch this footage. Obviously, we’re not using graphic images or footage, but we all watched it many times.

It’s also really difficult doing outreach and speaking to people — which we did in Uvalde many times — because that community is still suffering from what happened. In addition, public officials have not been forthcoming with information. And so, although we’ve tried to run many of these things by them or obtaining or clarifying certain things, that has been an ongoing obstacle. Trying to piece these things together, given the nature of just how awful it was and remains, I think, was really challenging for all of us.

Juanita: In terms of the film, there’s so much footage. So it was just making sure we actually watched everything, and we’re actually telling a story that is comprehensive and takes into account all of the things that we have available. I think the fact that it’s so hard to watch and it’s obviously very sensitive made us go back a couple of times and think about what are we watching and why? What are we showing and why are we showing it?

There were a lot of moments that are extremely powerful and help you understand what it was like to be in that building. But we didn’t want to re-traumatize the families. And so we ended up taking those parts out because more than just being very emotional and hard to watch, when it comes down to information and the reason why we’re doing the film, those didn’t really fit.

The narrative in the documentary unfurls mostly from the police officers’ perspective. Could you tell me about how that came about, Juanita?

Juanita: It’s very unique to have access to such a vast amount of footage. On anything that has to do with law enforcement, there’s a lot of restrictions, always, to interview them, but even more when it comes to body cameras. So we just wanted to use it in a way that would give people a better understanding of what happened through the eyes of law enforcement.

Lomi, you and your colleagues also wrote a long article about the response that not only looks at the experience of the officers, but also the kids and teachers who were at Robb Elementary that day. What did you learn about what they went through?

Lomi: I think how the film and the article really complement each other is that the film really gives you an insider look at exactly how that law enforcement response plays out. The article gives you a little bit more of two sides of the door. It has more of what the children and teachers were going through, and includes slightly more about some of the training requirements and what we found in our reporting about what is asked of officers and teachers and students across the country. But I think the two really complement each other well because one of the very, very surprising things that we both found throughout reviewing the body camera footage and the interviews, was just how many officers mentioned that they didn’t think children were inside that building because it was so quiet. And then you have all these interviews from the children saying that we were quiet because that’s our training.

Read more: “Someone Tell Me What To Do”

Your investigation revealed that the police who responded to the shooting in many cases didn’t follow best practices for dealing with an active shooter and there was a breakdown in communication. Are these types of failures common in such situations or was this case an outlier?

Lomi: As part of the team that worked on this project, we also looked at the responses to past mass shootings, including Pulse in Orlando, Parkland in Florida, and others. And what we found is that these kinds of issues — which are communication issues, lack of incident command, failures of going in immediately and confronting the shooter — are not necessarily an outlier. It’s happened before.

And that’s partly why we think this is important to evaluate, because Columbine, which happened in 1999, was supposed to be this turning point of, okay, this is how officers are supposed to deal with mass shooting responses better. And I think that’s what makes Uvalde really important, is, one, we have the ability to show people how this went wrong. But two, we are more than two decades after Columbine and the responses and the failures and the mistakes still keep basically repeating themselves in some ways.

We see some individual officers who responded to the shooting were removed from their positions in the aftermath — including Chief Pete Arredondo. But have there been any structural changes to address the factors that resulted in such a chaotic and delayed response? And if so, what do these efforts look like?

Lomi: After Uvalde, the Texas legislature last session passed a law that now requires 16 hours of active shooter training for all officers in the state every two years. That actually makes it the strongest law in the country at this point, which is what we found in our reporting. The majority of states don’t require by law any repeat training after a police officer graduates from the academy. The law only happened after the shooting, but it is a huge change. And it puts Texas as kind of a leader in training as far as active shooter responses go. For the rest of the structural changes, the city of Uvalde has told us that they have expanded training, and they’ve purchased more equipment like breaching tools and shields and other things that some of the officers said inhibited their response that day.

What we heard from experts who train officers is that they’ve not been able to include lessons from Uvalde because they’re still waiting for those findings to be made public.

Have you seen any legislative efforts in other states, aside from Texas, to require more active shooter training for police officers?

Lomi: I think we’re definitely seeing a trend. After Uvalde there were several states that made attempts to start requiring training more, not necessarily by legislation, but by regulation or other ways. It was kind of a wake up call, is what many of those state officials told us. It’s still a little bit of a patchwork — it depends on the state and by department. But I do think that a lot of states across the country looked at what happened in Uvalde and said we need to do something different.

What do you hope the audience takes away from this documentary?

Lomi: One of the things that I take away from it is that we always think that this just happens to other people. And what we’ve seen, what the pattern has been since Columbine, is that it can happen really at any time in places that you would never think. One of the things that officers and community members in Uvalde say is that they never thought it would happen in Uvalde. This is a city of 15,000 people. They had one homicide the year before the shooting. The officers were not necessarily prepared to handle this kind of onslaught.

I do hope it makes people think why does this keep happening? What can we do to stop it? And what can we do to just prepare better for it?

Juanita: School shootings have been on the rise for years in the United States, and this is just an insight into what it’s like for law enforcement to go through it. I think it gives an understanding of how they feel and the things that they need to respond to these situations, starting with the type of weapon that the gunman might be using, and what it does to them when they’re responding. I think it’s just understanding what this situation might look like and what can be done to be better prepared or better equipped to deal with them in the future.

Watch the full documentary Inside the Uvalde Response:

Correction: This story has been updated to correct a misspelled name.

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