Transcript for School shooting survivor: 'Kids were bleeding out everywhere'

Reporter: Which was the second of the day. Yeah. Reporter: And then you run back into the building. Yeah, we heard gunshots. We took in some kids that weren't in our class and we hid in a corner. Lights were off, like, we practiced. Reporter: As you were huddled in the corner of that room, what were you all doing? Staying silent. Texting our parents. Yeah. Reporter: What were you texting them? Saying that we're on lockdown and, like, I love them. Reporter: I can only imagine what the texts back were. Did you yor parents text you back? Uh-huh. Reporter: What did they say? Stay safe. Reporter: And that's when you knew the whole thing was real. Reporter: Jonathan blank was in a classroom on the first floor. The gunman began to fire into the room. You can see his shoes there in this video captured during the chaos. When the second round went off, it just -- it was chaos. I went under a desk. We stayed there, I was laying down. Four kids in my class, they got shot. Two of them, I believe, passed away. I saw them on the ground after they were shot, there was blood everywhere. And it was just horrible. Reporter: And that video that we now have all seen, you're actually -- you can see your shoes, right? Yes. I was laying down, trying to just get as far away from the door, like, hide, as possible, and just take cover. We didn'tnow what was going on. Kids were bleeding out everywhere and we didn't know what to do with them and finally, the cops, we hear them screaming, we had to put our hands up. They came in with assault rifles, pointing them to make sure that no one, the shooter wasn't in our class. And they directed us to line up and they said, just make a right out of this class and run as fast as you can to the street and get away. And as I was making the right turn out of the class, I saw two kids laying in the middle of the hallway dead. They were just dead. Reporter: Two more kids. Yes. Two kids that just weren't in my class. Reporter: Mackenzie hill had gone to a restroom on the second floor, leaving behind her twin sister in the classroom. Mckenzie would see the gunman down the hall. She had no choice but to run into another room. She sent a text to her twin. So, when we get in the classroom, we were just sitting down, I had contact with my sister, and then -- Reporter: She would only learn later that her twin had survived. She told me she loved me. Reporter: How long was it before you heard from her? Like around ten minutes. And then I get out of the school and I saw my sister. Reporter: What was that like? It was the best feeling. If she would have died -- I don't know what I would have done. We got separated, I was supposed to be in her class. Reporter: Jaden Blair told us about hiding in a closet. I just said, mom, I love you so much, I think I'm going to die. Reporter: How many of you know someone who did not get out alive? Really? So, all of you knew someone. Reporter: She then shows me a picture of her friend, Joaquin. And then, the other students begin pulling out their phones, the pictures of the friends they lost. Jonathan shows me Nick. This is my classmate Nick. He was actually on the national team for swimming. He committed to the university of Indianapolis a couple, like, two weeks before this happened. Great classmate, great person, always so nice. Reporter: How terrifying was the whole thing? It was the scariest moment of my life. I've never experienced anything like that. Reporter: I'm sure you think now about all the other shootings, too, in this country. Yeah, you never think it will happen to you, and, like, to your school until it really does, and it just doesn't feel real. And our entire team will not forget that moment inside that house when we asked how many of you know someone who was lost, they all raised their hand. And then began pulling out their phones with pictures of the friends they won't see again.

This transcript has been automatically generated and may not be 100% accurate.