Latest in the investigation. Nightline will be right back. Custody. His obsession with guns and the latest in the investigation. Nightline will be right back. Team usa to south korea we cant fly. But you know who can . Helping superheroes fly. United. Good evening. Thank you for joining us. Another Horrific School shooting echoed across american, 17 killed in parkland, florida, a city listed just days ago as one of the safest in the country. Tonight we hear new detail s about the suspect who is now in police custody. We could see the panic from a distance. Frightened. Reports are just coming in. We dont have a lot of information. We didnt know the who, but collectively as a nation we all feared the what. Theres an active shooter situation situation in south florida. [ bleep ] oh, my god that rapid roar of death and dieing. In another american school. Does he know where the shooter is. We dont know but were heading into the building. The first 911 calls came just before Marjory StonemanDouglas High School led out for the day. Police, fbi and atf all descended on the scene. We cant get hold of her. Have you called and texted and nothing has come back. Girlfriend got shot we heard. There was panic. Confusion. Parents desperate to find out had their child survived. Its devastating. Im sick to my stomach. We have multiple casualties. A line of ambulances in place of the school busses. Backpack as brandoned in a heap. We were just praying and crying, and i dont know how were alive. Hours go by. Students finally reunited with their family and by evening 17 dead, 14 injured, and more about the alleged student, a former student, nikolas cruz who stole so much from so many. Come to the conclusion this is absolutely pure evil. Students detailing those traumatic moments from inside. All we heard was the gunshots. We heard the gunshots and hid in the tennis courts. Talking about what they did as gunfire echoed in the hallway. Heard like a garbage truck banging. We hear boom, boom, boom hear screaming and we jumped under teachers desk. Swat teams can be seen searching the perimeter. Were monitoring the suspect. He went from the third to second floor. May have a gas mask on. Students barricading in classrooms, closets, anywhere they could hide. Need everyone down. As officers go room to room. Put phones away. Some recording disturbing videos of the mayhem many texting their parents. She keeps telling me be safe stay away. Im telling her no im your mother im not staying away. Outside controlled a chaos, High Schoolers streaming out of the building hands over their hands for safety. I heard someone down the hall say help me come save me. Just after 3 00 p. M. The shooter is still at large. White male. Burgundy shirt wearing black hat or long black pants mixed in with a group of students running west bound. Authorities said he got out of the school by blending in with others who were trying to escape. Its not uncommon for thieves, like robbers, to try to blend in with the crowd and try to escape. Somewhat unusual with mass shooters because vast majority of time they kill themselves or force Law Enforcement to kill them. Students outside, breathless, heart wrenching reunions, others waiting for answers, some student and staff unaccounted for. The family keeps texting her and shes texting back thank god. Are you going to leave. Well leave when she comes out. What did she fell you. Shes crying. Cant say anything. Shes crying a lot. This student recalls seeing teacher shot. We saw his body for like 30 minutes. We were just like praying, and crying and, then the police came and we just got out. This is the day we prayed would never be here in Broward County but were going to deal with it as a community. Around 4 00 p. M. The alleged gunman taken down in this video, sourced identified him as 19yearold former student nikolas cruz. He was a former student of Douglas High School he got expelled for disciplinary reasons, i dont know the specifics. The school represented something to the shooter. This is not the first time this has happened. Think of adam at sandy hook who walked into Elementary School he attended years before, because there was something about that school that he wanted to destroy. Sadly, he did. Tonight new information about the alleged shooter, a Family Member telling abc news, cruz was adopted with his younger brother, both of those parents now deceased. A former class mate called him quiet. That he had a interest in weapons. I knew he was into guns. Hes like a country kind of boy. Last year had a lot of conflicts in school. Got in a fight with one kid and from what i know he wasnt allowed to bring his backpack because they found bullet casings in it. I told my parents last year every week i was scared this kid might do something. If you take somebodys access to firearm and the fact they talk about fighting or have been in fights now you start to put the pieces together and connect the dots of an individual who may have predisposition to commit an attack like this. Authorities say the suspect used an Assault Rifle and began shooting outside before continuing inside. He had countless magazines, multiple magazines. And one ar15 rifle. Sounds like there was a fire alarm that was tripped. Big question will be whether the suspect triggered the fire alarm, if that was done to get the students to come out of the building and then the suspect was then starting to shoot at the innocent students coming out that would indicate there was planning on his part. Todays shooting marks the 18th School Shooting this year in a nation with average of 300 mass shooting each of the last three years. Thats at least four shot in each incident. Too soon since the mourning of las vegas those that were killed at First Baptist church in sutherland springs, texas. As a parent it scares me to death that this body doesnt take seriously the safety of my children. Connect senator chris murphy who represented the state sandy hook happened five years ago was on the floor when news broke about todays killings. It only happens here not because of coincidence, not because of bad luck, but is a consequence of our inaction. President trump also responding, tweeting no child, teacher, or anyone else should ever feel unsafe in an american school. No parent should ever have to send their kids to school and have them not return. That should not happen in parkland, it shouldnt happen anywhere in this country. School shootings are no longer new in america. Each one still numbering. We send our children to school to learn, not to die. Next, how communities across the country are preparing for the worst. Schools and Law Enforcement running active Shooter Drills. Running active Shooter Drills. Life goes on, yes, life goes on. Ive always wanted to share a special moment with my mom. I think surprising her with a night ski trip would just be the biggest gift i could give her. Lets make that happen. Shes gonna be so excited. Take me where i want to be. Let me dream, oh, let me dream. If you could see your cough. Its just a cough. Youd see how often you cough all day. And so would everyone else. Robitussin delivers fast, powerful relief to fight your cough in 12 hour shifts. Robitussin 12 hour cough relief, because its never just a cough. Robitussin 12 hour cough relief, your plaques are always there at the worst times. Constantly interrupting you with itching, burning and stinging. Being this uncomfortable is unacceptable. Im ready. Tremfya® works differently for adults with moderate to severe plaque psoriasis. With tremfya®, you can get clearer and stay clearer. 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Make the dream yours. There are two types of people in the world. Those who fear the future. And those who embrace it. The future is for the unafraid. Hey hun. Look at all this extra room i have on this king size ikea bed. Are you wearing a. Duvet cover . Why yes. Yes i am. Wheres mom . We finally redid our bedroom and shes prettttttttttty into it. Whats your dream . At ikea, we help you live it. Make the dream yours. School shootings like the one in florida today are becoming so common that many schools across the country are actually training for them, drilling students where to go if they hear gunfire and how to spot when a shooter is out of ammo and in some cases staging dress rehearseals. Heres abcs david wright. Can you tell where the shooter is . We dont know but were running in the building. Today the unthinkable happened again. Im sick to my stomach. One injured person hes shot. Unfolding this time at Marjory StonemanDouglas High School in parkland, florida. I just heard a few bangs. Went out for a fire drill and all i heard were gunshots. The suspected gunman, just 19 years old on a rampage. Kids fleeing the school, their hands in the air. Our have seen this so much that they know to raise their hand when theyre walking out so that officer can ensure that you are not complicit involved in this shooting. The shooter was still on the loose at that point. We have multiple swat teams. Police unsure where the weapon is collect every students backpack. This is a terrible day for parkland, Broward County and the united states. Events like this continue to happen. In dozens of counties across the country. So american Law Enforcement and teachers are getting to be experts in responding to deadly incidents like this. Minutes and seconds matter because so much damage can be done by the type of weapons that are available in our country. Semi automatic highpower rifle. The capacity to hold more bullet in the magazines creates this dynamic of multiple tragedies. Todays School Shooting ranks among the top five deadliest to date in the u. S. In schools across the country lock down drills are common as fire drills. Im going to kill everybody nobodys getting out. Some go as far as covering student in fake blood and recruiting volunteers to make it more realistic. Attention. This is a drill. We need to lock down. In 2014 we embedded at Sky View Academy in colorado as they went through the standard lock down drill. Please go behind my desk. The teacher locks the door and pulls the shade. Everyones told to keep quiet. Its kind of scary, huh . Kind of yeah. The kids huddle quietly. Do know why they do this did drill. To practice in case anyone comes here. Do you worry this scares students. We do but we practice enough that we hope that students are and staff is getting used to the idea. We have to. How long do these go for. Five minutes is longest weve had. Teacher holley carpenter supported these drills shes a graduate of columbine high school. When you look at those kids are you always thinking someone could come take their lives. No i look at those kids and think how great they are, how lucky i am to teach them, and i think wonder what theyre going to be like when they grow up. Hd its why she went into teaching and its is why she take these drills very personally. I always get a lump in my throat its not about flash backs of columbine its about the thought of anyone even wanting to hurt the kids. Sky view academy doesnt just do the basic lock down drill while we were there the teachers were getting a new method of training. Nobodys getting out. Teaching everyone not just to duck but to respond. Active Shooter Training is the new normal and because these incidents are repeating themselves, escalating and were learning lessons from failures in the past. How did you feel . Way more empowered and lots of adrenaline. Joe is a former Swat Team Member who has responded to active shootings for real. This open. Whats that mean . Hes teaching them how to recognize when shooter is reloading his gun. Hes out. Right. And teaching defense tactics. There we go. Good. Good. How to take down a shooter. First responders do too back in 2016 night line embedded with the Douglas County sheriffs department. As they conducted an active Shooter Drill in another colorado school. In a scenario this time more complicated. Shots fired. Hostages strapped to explosives and multiple schools on alert. Deputy and First Responders race stward toward the sound of gunshots down the stairs and hallways not knowing how many gunmen there are. Just as things are heating up at the high school another call sends deputies to a Different School up the street. Possible shooter at the school. Two deputies head in alone. No time to wait for back up. Inside helpless victim. One student chained to a bomb. These cops know their First Priority is to eliminate the active shooter. In this scenario hold up in a first floor bathroom. Drills such as this are no doubt Good Practice for the professionals. But is it fair to expect teachers and students to put themselves in harms way. Thats what we wondered at Sky View Academy. Is that one hundred pound student or teacher really going do be able to take down the 200 pound gunman. Lets find out. Joe is about 220. Pick out anyone in the crowd and see. Lets do it. So we got holley carpenter in her columbine sweat shirt to do it again. This time the guys going to fight back. This time the gunman resisting her effort to disarm him. She and other teachers dont want to be sitting ducks. Shes glad to have strategy she can use if her life is on the line. Hows that feel . Really good. This active Shooter Drill ends with a different version, of duck and cover, this time everyone arms themselves with a tennis ball but in real life might well be a hole punch or desk, chair, or dictionary. This time its the active shooter whose the sitting duck. Would this works if the bullets were real or if this were a class full of kids, hard to know. But unfortunately with every incident like today in parkland florida, more and more communities figure better safe than sorry. Im david for nightline our thanks to you david well be right back. saved money on motorcycle insurance with geico goin up the country. Bowl without me. Frank. im going to get nachos. Snack bars closed. Gah ah, ah ah. Im goin up the country, baby dont you wanna go . Im goin up the country, baby dont you wanna go . Geico motorcycle, great rates for great rides. I. Prilosec otc 7 years ago,my doctor recommended. 5 years ago, last week. Just 1 pill each morning, 24 hours and zero heartburn. 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