GWEN IFILL: Now a unique look at school safety issues through the eyes of young people.

Today, we're launching a new feature from our network of Student Reporting Labs, middle and high school journalism programs around the country. It explores how the concept of safety has been redefined since the Sandy Hook tragedy two years ago.

Our first report comes from student television network correspondent Sydney Payne at Carlsbad High School in California.

As part of our series on what's changed, she and her team visited a local San Diego elementary school that was the scene of a terrifying shooting in 2010.

We're calling the series The New Safe.

SYDNEY PAYNE: Friday October 8, 2010, began as any other day begins at this suburban San Diego elementary school. It was lunchtime, and the students were heading out on to the playground.

At about the same time, 41-year-old Brendan O'Rourke pulled up to a curb outside the school. He was armed with a .357 Magnum revolver, a red gasoline can and a propane tank.

BARBARA SWEARINGEN, Administrative Assistant, Kelly Elementary School: It was a typical Friday. Everyone was wearing their spirit wear. It was very relaxed and we heard what we figured later was the last gunshot.

TRESSIE ARMSTRONG, Principal, Kelly Elementary School: We heard over the walkie-talkie the custodian was yelling that somebody was shooting at the children.

CARSON SCOTT, Student Eyewitness: There was a loud bang and everybody thought it was just like a big firework. And so just everybody is looking up, like up over there, because that's where he was. Everybody just, like, looked up at everything, and nobody knows what's going on. And then a few people started screaming and then everybody starts screaming.

SYDNEY PAYNE: It's lunchtime, and Carson and his friends are out on the playground. The loud ping that he hears is actually the sound of a bullet from a .357 Magnum handgun hitting this metal pole, only about 10 feet away from where Carson and his friends were playing.

CARSON SCOTT: I see a man who looks like he's wearing all black, like a black — like everything all black, like a beanie and a shirt and long sleeves. And he's just running with a gun.

KEVIN LEHAN, Sergeant, City of Carlsbad Police Department: He ends up shooting a couple rounds and ends up getting confronted by a school aide. At that point, he raises the gun, points it at her chest and pulls the trigger. Well, he ran out — he had a revolver. He ran out of ammunition.

SYDNEY PAYNE: Before running out of bullets, the gunman randomly shot six rounds into an open playground of children. Two girls, ages 6 and 7, were caught in the gunfire.

SGT. KEVIN LEHAN: His statements were, “Shoot them, burn them, blow them up.” And I don't think he was planning on just taking a couple shots and leave. I don't think that was sufficient for him.

SYDNEY PAYNE: Alarmed by the students' screams, three construction workers who were working on the roof of the school noticed Brendan O'Rourke as he climbed back over the fence. O'Rourke had run out of ammunition and he was heading back to his car to reload.

The men were able to wrestle him to the ground after one of the workers hit the shooter with his truck. Nobody at Kelly Elementary School ever expected something like this to happen here.

TRACY MARKS, Teacher, Kelly Elementary School: My life won't be the same, no. I mean, I worry when I send my kid to school, you know, that something could happen. It won't be the same. Our Kelly bubble was broken that day.

TRESSIE ARMSTRONG: I think, when somebody tries to hurt kids that badly and we love these kids so much, and you think that somebody tried to do that to them, it's emotional. That hurts me that that happened for them. And I'm also very proud of them, because kids are super resilient.

Peggy Parish teaches kindergarten at Kelly. As the school went into immediate lockdown, Parish ushered 15 students and three classroom helpers into a bathroom. They would stay there for the first 45 minutes of the nearly four-hour lockdown.

PEGGY PARISH, Teacher, Kelly Elementary School: About 45 minutes, we were all in this one bathroom, and then we had some go into the other bathroom after about 45 minutes.

And at the beginning, we were all just up kind of against the wall, and then, as time went along and as I was reading and doing lessons, I had to sit there on the floor.

SYDNEY PAYNE: Right.

PEGGY PARISH: And, so, yes, it was cozy. There were — it was tight.

SYDNEY PAYNE: Right.

Parents were asked to congregate in a nearby park. For nearly four hours, they would wait as law enforcement searched the campus, ruling out the possibility that there was a second gunman.

BARBARA SWEARINGEN: It was amazing to see them waiting in the park so patiently. They just waited. It was amazing.

SYDNEY PAYNE: Carson was asked to testify at O'Rourke's trial. His vantage point on the play structure allowed him to get a good look at the gunman. Four years have passed since the shooting at Kelly Elementary School. It takes time to heal, and for some, the process can be a difficult one.

REESE FELS, Student, Kelly Elementary School: I think that, what if it happens again? What if somebody comes again and shoots at our school?

PEGGY PARISH: Kids are going to be in school for a long time. And I don't want them to approach every morning as a place that they're going to a place that's scary. I want them to know that school is safe and that there are people, way more people who are good people in the world than people who might try to hurt them.

TRESSIE ARMSTRONG: Educators, not me, not just me, but everybody, the staff, would put their lives on the line for children. And when push comes to shove and there's a big situation, the adults who are caring for the kids will put their lives on the line for them.

And the public out there needs to be aware that educators are really dedicated to the kids in their care and we will do what it takes to make sure that they're safe.

SYDNEY PAYNE: The shooting happened on a Friday. Meeting over the weekend, the staff decided to reopen school on the following Monday. This would be the beginning of an extraordinary healing process.

TRESSIE ARMSTRONG: We decided that we really needed to celebrate a miracle, and not let this incident destroy us, but help us come together. We wanted to choose love over hate and courage over fear, because that's how this community works together.

SYDNEY PAYNE: While a few families transferred to other elementary schools in the district after the shooting, the vast majority chose to remain at Kelly.

KAYLA LEHMAN, Former Student, Kelly Elementary School: I decided to stay at Kelly because it is like — it really brought us all closer together. And I thought not to run away from your fear. I thought it was cool that, even after that, that I could come become and feel safe.

GWEN IFILL: You can see more student reports and the entire New Safe series on our Web site, PBS.org/NewsHour.