Social media have become essential for crisis communication. While past research has focused on their role in corporate communication, studies largely ignored how public organizations use social media. Among these, the police are a particularly relevant case due to their responsibilities in society. Using a sequential mixed-methods design that combines qualitative interviews with an automated content analysis, this study analyzes how the German police use social media during community (e.g. mass shootings) and organizational-level crises (e.g. misdemeanors within the police). The results demonstrate that Twitter and Facebook are the primary platforms for crisis communication, with their unique affordances shaping the communicative styles of the police. We also find police communication strategies to differ between the two crisis types. During community-level crises, the main goal of the police is to provide information in a largely unidirectional manner, while communication during organizational-level crises is more dialogue-oriented to prevent reputational damage.