abc's john quinones has the preview. >> there were a lot of failures that day. >> 19 children killedng with two teachers. the second-deadliest school shooting in u.s. history. >> we expect our police officers to run toward the danger. and we now know that's not what happened. >> it was treated as a barricaded subject, and instead it should have been treated as an active shooter. that's plain and simple. >> when it came to the moment of truth, they failed. >> he's in the class. >> the last thing you expect to hear is that 77 minutes went by before anyone reached that classroom. you had children calling on their cell phone, asking for help. >> i'm in classroom 112. please hurry. there's a lot of dead bodies. please send help. i don't want to die. >> reporter: the horrific events at robb elementary in uvalde, texas, stunned a community and the nation. as the world watched in those first hours and days after the shooting, officials made a series of misstatements and inaccuracies. >> they showed amazing courage by running toward gunfire. >> they did contain in the classroom, they put the

john quinones has been covering the story from the beginning. ories i've ever covered. story about heroism and survival. it's remarkable for an adult, but this was a 10-year-old child who showed incredible strength and bravery while trapped inside her school with a vicious gunman. her family, they say they want the public to see this. >> 911. >> there's a school shooting at robb elementary school. >> can you tell me your name? >> khloie. >> reporter: over a series of 911 calls this 10-year-old pleads for help. >> please hurry. there's a lot of dead bodies. >> we spoke about things like this happening around our nation. give them scenarios and what they would do. >> be quiet. >> i am, i am. i'm telling everybody but nobody is listening to me. i know how to handle these situations. my dad taught me when i was a little girl. send help for my teachers. they're still alive, but they're shot. >> someone is going to get you, okay? >> please hurry. i can't wait. i just wanna see my dad. >> okay, stay quiet. how many people are in there that are alive wit