Three studies examine the impact of an anger manipulation on threat perception among Northeastern University students after the Boston Marathon bombings. Data collection for one experiment began within 24 hours of the bombings. Results suggest that the impact of anger on threat perception differed during the week of the bombings compared to 1 and 5 months later. During the week of the bombings only, participants experiencing anger were less sensitive to the distinction between threats and nonthreats, and more biased toward perceiving all stimuli as threatening relative to control participants. We discuss potential mechanisms for these effects and the need for more rapid response research in the wake of incidents of mass violence.