When an accident has occurred, first aid before a professional response arrives can improve the outcome for the victims. However, little research has been done on the effect of coordination and leadership on first aid responses. This work-in-progress study reports an experiment using a simulated scenario, i.e. traffic accident, to understand the effect of coordination and leadership on first aid performance in ad-hoc groups of immediate responders. The results showed that coordination and leadership are significantly related to increased self-evaluated team performance while expertise and authority differentiation is not. These results provide a first insight to the coordination and leadership in ad-hoc groups of immediate responders, but more research is needed to validate these results. Structured performance evaluation with subject matter experts is planned as an extension to the present work-in-progress.