Mass shootings that result in mass casualties are almost a weekly occasion in the United States, which—not coincidentally—also has the most guns per capita in the world. Viewed from outside the U.S., it seems that Americans are not bothered by the constant deadly gun violence and have simply adapted to it. Yet, our analysis of the well-being costs of gun violence—using Twitter data to track real-time responses throughout the course of these appalling events—suggest that is not necessarily the case. We focus on the two March 2021 shootings in Atlanta and Boulder, and compare to similar data for the “1 October” (Las Vegas) and El Paso shootings a few years prior.