This paper investigates coordination and real-time information sharing across four emergency medical teams in a high-risk and distributed setting as they provide care to critically injured patients within the first hour after injury. Through multiple field studies we explored how common understanding of critical patient data is established across these heterogeneous teams and what coordination mechanisms are being used to support information sharing and interpretation. To interpret the data, we drew on the concept of Common Information Spaces (CIS). Our results showed that teams faced many challenges in achieving efficient information sharing and coordination, including difficulties in locating and assembling team members, communicating and interpreting information from the field, and reconciling differences in team perspectives and information needs, all while having minimal technology support. We reflect on these challenges to suggest an extension of the classic CSCW time-space matrix, as well as future development of CIS as an analytical framework. The paper concludes with design opportunities for supporting highly distributed and heterogeneous teamwork in time-critical work environments.