The current article examines the emergence and dynamics of leadership during an extreme situation—a terrorist attack at the foreign subsidiary of a multinational energy corporation—and the crisis response undertaken at the corporate headquarters. The inductive analysis reveals that the in-situ crisis leadership involved impromptu interactions between multiple individuals leading collectively. Multiple sources of leadership emerged to carry out four critical leadership functions, namely strategic framing, ad hoc structuring, relational coping, and instant developing. These functions were carried out by several formal and informal leaders together, enhancing the overall leadership capacity in the crisis management organization (CMO). With increased capacity to lead efforts in different domains came specialization, which could have led to misalignment and fragmentation. But this was avoided by leaders acting as “role boundary transgressors,” expanding the boundaries of their responsibilities across roles, functions, and levels to foster the alignment of collective efforts across the CMO. Based on rich data from a leadership situation that researchers rarely have access to, this study contributes to the understanding of leadership during extreme situations by illustrating who leads (the emergence of multiple leadership sources), what leaders do (leadership functions), and how leadership plays out over time and across levels (through dynamic role boundary transgressions).