In the aftermath of Hurricane Katrina, the city of New Orleans witnessed an emerging conflict between the residents who survived the storm and the rescuers charged with assisting them. This particular type of inter-group conflict has not been documented before, as it uniquely entails survivors acting against their very self-interest, and rescuers subverting their helping roles. We argue that Drury and Reicher's Elaborated Social Identity Model explains the nature of the inter-group aggression. Drawing on published first-person accounts, we document how the power differential between rescuers and survivors shaped inter-group perceptions and eventually rendered inter-group aggression acceptable. While inter-group aggression reflects only one facet of the aftermath of Katrina, we conclude that it must be interpreted as meaningful social action commensurate with the groups' emerging collective identities.