Random acts of violence frequently hit the US news. It can be tempting to pull these outliers out of context. Cynicism and mistrust of our fellows may soon follow a hyper-focus on tragedy. Despite what our emotions might warn us after a tragedy, the vast majority of people let goodness drive their actions. This is not to minimize the impact of violence, rather it's an effort to rally kindness and healing. We all must determine the level of risk for which we a comfortable, but perhaps having situational awareness will allow us to come out of our protective cocoons and enjoy life.
How does this relate to writing? Building realism requires understanding what constitutes an outlier. The impact of outlier behaviors increases when we let the consequences rest within realism. Which packs the punch, violence in a purely violent world or violence within a world hoping for peace? I'm not saying you can't write a dystopian world, but consider the consequences of the context and be sure your punchy scene isn't getting lost. Also, consider how situational awareness or lack thereof impacts the plot. Is lack of awareness a cheap plot devise or a fundamental aspect of the characterization. Set up is key, or it will come across as coming out of nowhere.