Transcript for Texas school shooting survivors on what happened when alleged gunman opened fire
And then out of nowhere we hear three gunshots. A lot of loud pops. Dove under the desk. There's a slight pause and you hear boom, boom. Then you realize what it was. Reporter: Desks as shields. Closets for cover. These are the war-like stories from inside America's schools. Always kind of feet like eventually it was going to happen here too. I wasn't surprised. I was just scared. Reporter: This time it was in Santa fe, Texas, a small town outside Houston. More shots fired. Additional shots fired. Reporter: The barrage left ten dead, eight students and two teachers, and injured 13 when an alleged gunman opened fire inside a high school art class on Friday morning. They're having a shooting at the high school. I have an officer down. Shooter not in custody. Reporter: Those haunting images we have seen too many times before, a uniquely American phenomenon. The telltale signs of an all too common problem afflicting our country's schools. Part of what some call a public health crisis. School shootings now are at epidemic levels. They're increasing in frequency and in lethality. Reporter: The students at Santa fe high had just started the school-day when a fire alarm rang out. He's actually shooting. He's in the art room. We've got, we've got shots fired right now, guys. Reporter: 15-year-old Isabel lamats was inside that art class. At first I just froze because I didn't really know what was going on. And we ran to the back door, but it was locked that day. I then ran to the ceramics room which I was pushed into by other classmates, and I immediately hid. Reporter: On the floor S calls the police and then her mother. And I heard her say they're shooting up the school, I'm hiding in a closet, I love you mom. And gunfire in the background. Reporter: Survivors sate alleged gunman taunted his victims after shooting at them. Zplefr time he'd kill someone he'd say "Another one bites the dust." What was his demeanor like? He was calm and excited. He was cheering himself on. My friend told me that he could hear him singing. Reporter: Police and paramedics respondingwithin minutes, taking fire. Officer down. Reporter: With the suspect still on the loose. We need coverage on the outside. We believe he's barricaded inside. Everybody needs to clear out this way. Reporter: Teachers ushering students away from the scene. Isabelle still hiding in a closet. That's when he shot through the glass and the door, and that's when he shot four people. Reporter: New details about what happened inside the school. Two officers engaged in a shootout. Heroes from that isv engaged this individual at approximately four minutes and stayed engaged with him, keeping him contained. Reporter: Shortly after 8:00 A.M. The suspect, wearing a trenchcoat and combat boots, surrendered. There are two weapons. One was a shotgun, and the other is a .38 revolver. Reporter: But the danger was not over. There have been explosive devices found in the high school. Reporter: Authorities say that even more explosives were discovered at the suspect's home. Although investigators say it's unclear if they would have funktsed. One was a CO2 device. Another was a molotov cocktail. And there's various other types of explosive devices. Reporter: The suspect a student at the school he allegedly attacked, a junior who was a football player and had even been on the honor roll. Authorities say he had no prior criminal record. His slate is pretty clean. And so there simply were not the same type of warning signs. Reporter: Tonight new details trickling in about the 17-year-old now behind bars. Right now he's in the galveston county jail under suicide watch. In there for capital murder. 17 years old. Reporter: Speculation over perhaps missed signs. Just last month he posted this photo of a t-shirt with the slogan "Born to kill." And possible motives, 16-year-old Shana fisher may have been targeted for rejecting the alleged shooter, says her mother, Sadie Rodriguez. She finally stood up to him because they kept getting more aggressive and aggressive. Reporter: But his attorney denying those claims. I've spoken with the d.a.'s office about it and there's no information to support that claim. Reporter: The suspect's father telling the "Wall Street journal" his son is "A good boy who was bullied at school," adding "I believe that's what was behind the shooting." The father saying, "It would have been better if he shot me than all those kids." Police say the father's guns were used to carry out the attack. It does appear the guns were kept in a locked -- a locked gun cabinet or gun safe. Reporter: And authorities now telling ABC news that the suspect may have studied previous mass shootings, allegedly incorporating aspects of those massacres into his own attack. Many of these mass killers are studying the work of previous killers and trying to outdo them literally. It's disturbing, it's scary, but it's quite real. Reporter: A recent FBI report shows active shooter incidents have increased significantly since the turn of the century. From 2000 to 2006 we averaged around six active shooter scenarios annually. Last year there were 30 active shooter scenarios in this country. That's five times the pace of when the FBI first started studying. Violence is particularly copyable because it's so what we call salient, it's so emotionally driven. Reporter: Dr. Gary Slatkin is an epidemiologist formally with the world health organization who now focuses on gun violence, a problem that he says often has a pattern. People who are feeling a certain way, unhappy, have a grievance, feeling socially disapproved of, and they are the people who are the most susceptible to the exposure to violence. Reporter: But unlike other diseases, slutkin says gun violence is the one epidemic that public health experts have had no voice in and could play a key role in solving. The bread and butter of epidemic control is to find rare events in the community and to stop them from becoming full-fledged events. Reporter: Today a moment of silence at the growing memorial in front of the school. As the familiar thoughts and prayers and some calls for change once again echo, this last night from Texas native Kelly Clarkson at the billboard music awards. And I'm so sick of moment of silence. It's not working. Like obviously. So -- sorry. So why don't we not do a moment of silence? Why don't we do a moment of action? Reporter: Isabelle is now at home with her mother, who says for them it's time to heal. I don't know what drove him to this. The problem is it sounds like nobody did. Which means that we as a community or his parents or whoever, they failed this child at some point. And sadly this was the outcome. And I don't know the answers. I do know we need to figure it out as a whole. Reporter: Too many once again mourn their losses. Like those of Aaron Kyle Mcleod, a 15-year-old honor roll student. Sabika sheikh, an exchange student who was supposed to go home to Pakistan in just a few weeks. And Cynthia Tisdale, a substitute teacher. For "Nightline" I'm Marcus Moore in Santa fe, Texas. Texas governor Greg Abbott will be holding roundtable discussions on school safety starting tomorrow.
This transcript has been automatically generated and may not be 100% accurate.