SCOTT SIMON, host:
Ten years ago on Monday, two boys went on a shooting spree at Columbine High School, and they killed 13 people at that suburban Denver school before taking their own lives. Many students witnessed the killings and then had to deal with the repercussions.
Ms. KIM BLAIR: It's one o'clock Monday morning. I'm awake again. I just wish I wouldn't have any more flashbacks. It's the hardest part.
SIMON: That's a young woman named Kim Blair from a 1999 audio diary. Colorado Public Radio gave Kim a tape recorder so she and her twin sister Patti could describe how they were feeling in the days after the attacks. From Colorado Public Radio, Zachary Barr has more.
ZACHARY BARR: Ten years on, the audio diary is still hard to listen to, even with a high school girl's pop music playing in the background. Here Kim recalls that on the day of the shooting she was eating lunch outside alongside two friends.
Ms. BLAIR: And we were sitting there talking and we saw Dylan and Eric come. I saw them put down the bags and they started shooting. Ann Marie was the third person I had seen shot.
BARR: Kim's talking about Ann Marie Hochhalter, her best friend at the time. Ann Marie survived, but was paralyzed. Two others outside were killed. The shooters, Dylan Klebold and Eric Harris, later stormed the school's library, where Kim's twin sister Patti was studying. Patti heard the gunmen approaching and hit the floor.
Ms. PATTI BLAIR: My friend and I were under the table. And they came over to our table and Eric glanced underneath our table with his gun and just stood back up and walked to the table behind us and shot the people there.
BARR: Ten people died in the library, but the killers chose not to shoot Patti.
Ms. P. BLAIR: I knew I had a guardian angel that day. I just don't understand why those other people in the library did not.
BARR: A few days after the shootings, Patti's home watching a gory movie where high school students battle giant alien bugs for control of the universe, and twin sister Kim is flabbergasted.
Ms. K. BLAIR: Patti, gosh, I came home today and she's sitting on the couch watching "Starship Troopers." Okay, how much more violent do you want to get?
(Soundbite of movie, "Starship Troopers")
Ms. K. BLAIR: Maybe she's okay with seeing violence and stuff like that, but I'm not ready for it.
BARR: The audio diary covered the first few weeks after the tragedy, then the diary ended. Talking to the sisters today revealed something surprising. It turns out Patti's decision to watch "Starship Troopers" was one part of a calculated plan. She had prescribed herself heavy doses of fake violence.
Ms. P. BLAIR: Literally, I would watch a movie like every night or actually even a couple times during the day just to desensitize myself.
BARR: Patti's recovery plan went way beyond action movies. For about a year, Patti flooded herself with sights and sounds that made her fearful: crowds at the mall, fire engines with sirens blazing, even insisting a friend shoot off a paintball gun while she stood by.
Ms. P. BLAIR: My whole entire family thought I was completely nuts, but what people don't understand is any sound nearby just reacts to me and then goes into, like, alert mode, and you almost had, like, a panic attack. And so I did everything possible to help myself and to get past that emotion of always being on, you know, alert all the time.
Ms. K. BLAIR: I dealt with things a bit differently than Patti. I made sure that I was extremely busy.
BARR: Kim filled her time caring for others, concerned about how they were dealing with the trauma. That left little room for herself.
Ms. K. BLAIR: I didn't cope with it for a while. I just kind of put it in a box and didn't - and chose not to deal with it for a while. But I ended up, you know, being diagnosed with depression and PTSD, which I think everybody in the building at that point had.
Ms. P. BLAIR: Yeah.
Ms. K BLAIR: It was like an epidemic.
BARR: Here, the two women laugh a little, recalling the days when it seemed like their entire senior class had Prozac in their backpacks. But that was almost 10 years ago. Now Patti's a computer programmer, and Kim's a teacher. Both say time has helped a great deal. The flashbacks have gone away, and they don't constantly think about those who died. For Kim, this year's anniversary is a turning point.
Ms. K. BLAIR: This is the year that I think we can finally put it behind us and start seeing it as a piece of our lives and not having it be our lives.
BARR: Patti agrees.
For NPR News, I'm Zachary Barr.