Negative thoughts

I have been having some bad panic attacks regarding school shootings especially with the recent ones. I’m not so much scared for myself as I am for my little brother, I just don’t know what I would do if anything like that were to ever happen, I’m so scared for him when he goes to school. I can’t stop having these terrible thoughts that i’m gonna say bye to him in the morning and something terrible will happen while he’s at school. I just can’t shake the horrible feeling, if anyone has any advice on how to stop thinking about it or worrying so much about it, it would be really appreciated. Thanks glow community.