School anxiety

As I’m getting deep into my RT program, I'm having a lot of difficulty with school anxiety. When it comes down to doing something like studying at school, retaining everything during lectures, or even taking a test at school, I notice I have such a hard time. My school does some hybrid tests where some tests are at home with the honor lock system, and I always get better scores than the ones at school. If anybody has any advice on how to overcome this anxiety, I deeply appreciate it :((. My classmates always invite me to stay after school and join them for a study group but I always have an immensely difficult time. I do have an idea of what the source of my anxiety may be, I’m not afraid of failing at all, what really consumes me in school environments, is this immense fear that someone at any given moment could come in and end my life. When I was younger a gunman came into my elementary and killed one of my teachers and another student, and after that if I’m being honest I felt fine. It was a traumatic experience but I’ve always tried to push it in the back of my mind. But more recently I can’t help to feel this immense amount of anxious. I’m hoping one of you have some advice to overcome this feeling :,)