This case study discusses the treatment of an emergency responder to the 2007 shooting on Virginia Tech’s campus where 33 students and faculty members were killed. After a thorough assessment, prolonged exposure (PE) was used to treat the emergency worker, referred to as Jack, for posttraumatic stress disorder (PTSD). Assessment measures administered at the conclusion of treatment, 1 month post-treatment, and 6 months post-treatment suggest that the treatment gains were maintained following the culmination of treatment. The primary aim of this article is to provide support for the effectiveness of PE among emergency responders who develop PTSD. In addition, this case presentation is particularly important given the prevalence of mass shootings in the United States. Several complicating factors, including a delay in treatment seeking, arose over the course of treatment and are discussed.