To explicate the qualities of cooperation among leaders and their organizations during crisis, we studied the response to the 2013 Boston Marathon bombings. Through interviews and analysis, we discovered leaders successfully overcame obstacles that typically undermine collective crisis response. Qualitative analysis revealed five guiding behavioral principles that appeared to stimulate effective inter-agency leadership collaboration in high stakes. We draw upon concepts of collective leadership and swarm intelligence to interpret our observations and translate the findings into leader practices. We focus on replicable aspects of a metaphenomenon, where collective action was greater than the sum of its parts; we do not evaluate individual leader behavior. Our findings provide a starting point for deeper exploration of how to bolster public safety by catalyzing enhanced inter-agency leadership behavior.