Transcript for School shooting leaves 2 dead, shocks Southern California community
Friday morning as we deal with another school shooting. Hard to believe we are talking about that again, of course, we do want to begin with that shooting this morning there in California. Two students were killed and three others injured. The suspect, a 16-year-old boy, is now in custody in critical condition this morning. Matt Gutman is outside the high school in Santa Clarita with more. Reporter: Good morning. This morning investigators are trying to look into two things, first, what was the motive, what drove this 16-year-old boy on his birthday to try to go into his school and murder his classmates? The other is, where did he get that 45 automatic pistol. He unloaded the entire magazine. It took just 16 seconds to throw this entire community into chaos and grief. This morning, another American community about to bury its children. We've got an active shooter at saugus high school. We need all units. Reporter: This school shooting north of Los Angeles. Police say a male student came into the school just after 7:30. Male Asian wearing a black hat and blue jeans. Reporter: With a backpack and murderous intent. Using a 45 semiautomatic pistol he shot five students them himself. It took just 16 seconds. Dozens of police cruisers and S.W.A.T. Teams swarming. Students inside taking cover. Everyone was panicked. We turned off the lights and locked the doors and sat and waited. Reporter: They didn't know it was over for that a 14-year-old boy and a 16-year-old girl would be killed. I have one down inside the office and I need paramedics right now. Reporter: 17-year-old Hayden trawlbridge said he'd been drilling this with his parents since he was 4 years old. You practiced this. Yeah, they told me don't -- your first instinct grab something you can hit someone with just in case and like put a book in front of your chest to protect from stuff like that. Reporter: Many students texting parents. One girl write, mom, I don't know what's going on here at school but I love you and I'm so thankful for everything you've done for me. I love you so much. Amidst the sirens and S.W.A.T. Teams, terrified parents. Hands over mouths, many with tear-streaked faces waiting to hold their children. Students led out of school. Some hands in the air there in line was Dana Martinez, her dad cutting in for a hug. You're crying now. Is that because you're so relieved. I'm just so relieved. Reporter: Choir teacher was barricading the class when Addison was rushed in, shot in both the hip and shoulder. We cleared a space for her and I wrapped the wound on her shoulder. She did have another gunshot wound. I should have never had to treat a gunshot wound as a choir teacher and there's something really wrong and something has to change because I held a bleeding child today in a room with 40 sobbing children. Reporter: Addison now recovering. The girl's aunt is also a teacher at the school and says she already evacuated when she heard her niece had been shot. Then my husband is the one who texted me to let me know that Addie was one of the kids shot. She's doing well and she's stable so she's going to be okay. Reporter: And that is good news but one thing that struck me is that teacher was able to treat the wounds of that student in her class because there was a trauma kit in that classroom. This is what it is. It is called a keep the pressure kit inside a blood clotting agents and big bandages provided by a nonprofit to every single classroom in this entire school district. That is shocking and depressing but I suppose it's good to learn one of these may have saved a student's life here yesterday. Cecilia. But to hear that choir teacher say it best, something has to change. Okay, Matt Gutman, thank you.
This transcript has been automatically generated and may not be 100% accurate.