Recent scholarship finds that exposure to mass shootings has no effect on Democratic vote shares. While arguably a reasonable proxy for public demand for heightened gun control, this outcome nonetheless reflects myriad issue concerns, with guns being just one issue typically dwarfed in importance by the attention given in electoral campaigns to jobs, the economy, and other social issues. Our research improves the issue-domain correspondence between treatment and outcome by analyzing voting directly on gun policy. We leverage a mass shooting that occurred in Washington state shortly before residents voted on a ballot measure to regulate firearms. Critically, a previous measure on firearms appeared on the ballot in Washington 2 years prior, enabling our analysis to control for pretreatment support for gun control. Across various model specifications, we find that proximity to the shooting was associated with increased support for gun control. We replicate this finding with three additional shootings.