I've never heard a kid mention it, but I do live in Utah, maybe they feel more secure here. But while teens are aware of school shootings and may say they are concerned about it if you ask them ... I don't think it's really on their mind often enough to significantly be affecting their mental health. The causes has to be something much more of a frequent, daily kind of stress on their mental health. Social media I believe is a strong variable here, mostly because of how it amplifies continuous feelings of insecurity, body image concerns, social anxiety, etc.