I understand your comments.
My first impressions were:
1) Perhaps she was involved in it somehow or knew who was.
2) WHERE is this place? Some locations in this great USA are exceedingly dangerous and some people keep their emotions at bay in order to survive.
3) She's working in a pharmacy. The 'wonder drugs' available today are designed to keep people functioning in the face of 'Post Traumatic Stress Disorder', 9-11 and more. I suspect they do so by cutting people off from their feelings. Perhaps she's taking one of them.
4) If she walked into a situation where the victims were alive and being cared for, the police and EMT's clearly had the situation under control and everyone she worked with was right there, and a bunch of reporters were also right there, maybe she didn't feel scared. Maybe she felt curious or perhaps like she needed to be strong.
5) Some people don't feel their feelings till later when they're alone.
6) Some people think it's shameful to express weakness or fear or vulnerability.
7) Maybe she's a JW and has no meaningful emotional connection whatsoever to anything.