This research evaluated the effectiveness of the Eye Movement Desensitization and Reprocessing (EMDR) Protocol for Recent Critical Incidents (EMDR-PRECI) in reducing posttraumatic stress symptoms related to the explosion in an explosives manufacturing factory north of Mexico City that killed 7 employees. The EMDR-PRECI was administered on 2 consecutive days to 25 survivors who had posttraumatic stress symptoms related to the critical incident. Participants’ mean score on the Short PTSD Rating Interview (SPRINT) was 22, well above the clinical cutoff of 14. They were randomly assigned to immediate and waitlist/delayed treatment conditions and therapy was provided within 15 days of the explosion. Results showed significant main effects for the condition factor, F(1, 80) = 67.04, p < .000. SPRINT scores were significantly different across time showing the effects of the EMDR therapy through time, F(3, 80) = 150.69, p < .000. There was also a significant interaction effect, condition by time, F(2, 80) = 55.45, p < .001. There were significant differences between the two treatment conditions at Time 2 (post-immediate treatment vs. post-waitlist/delayed), t(11) = −10.08, p < .000. Treatment effects were maintained at 90-day follow-up. Results also showed an overall subjective improvement in the participants. This randomized controlled trial provides evidence for the efficacy of EMDR-PRECI in reducing posttraumatic stress symptoms after a technological disaster.