With the establishment and growth of the Emergency Medical Services (EMS) subspecialty, significant attention has been focused on clinical activities performed by EMS physicians in the out-of-hospital environment. An EMS fellowship includes special operations education to develop preparedness for responding to field situations requiring physician expertise. With only a thousand Board Certified EMS physicians in North America, EMS physicians may not be available 24 h per day to respond to field emergencies. Non-EMS physicians with minimal experience in prehospital or austere care may be called upon to respond to complex prehospital emergencies requiring advanced skills. The Los Angeles County EMS Agency implemented a policy in 1992 to establish Hospital Emergency Response Teams (HERT) as a regional resource to provide time-critical, specialized prehospital services within an EMS system. Activation of the HERT is rare, most frequently prompted by need for field amputation to enable extrication. We describe one such incident of a field intervention by HERT and detail the staffing, training, and equipment considerations within our large regional EMS system.