This paper presents findings from field trials observing human-robot interaction between certified rescue workers and two types of tactical mobile robots at a rescue training site. Data was collected on how members of a fire rescue department directed the use of two types of robots for four tasks (climbing stairs to investigate condition of upper floors, searching dark, cluttered environments with two different sensor suites, and exploring vertical voids). The prototypical workflow, the type and frequency of errors during each task, how the robot workflow compared with existing urban search and rescue (USAR) practices, and any additional information that came out during debriefing is reported for each task. Two major workflow patterns that could be partially or fully automated were identified: stairwell search and topological search. In addition, collaborative teleoperation appeared to be an important multi-robot strategy. Rescue workers rated the robots' performance superior to existing methods for searching and for exploring vertical voids, but not for stairwells.