The November 13th Paris attacks were the most violent and devastating events to occur in France since World War II. A large number of persons are likely to develop PTSD or trauma-related disorders, especially victims directly involved, their families, as well as the the first responders. In this context, there is an urgent need to enhance treatment resources. Psychotherapy is known to be effective but it is costly, and require qualified professionals. Pharmacotherapy (e.g., selective serotonin reuptake inhibitor,SSRIs) is also considered effective. However, side effects often lead patients to abandon their treatment. An alternative evidence-based intervention is the use of the β-adrenergic blocker propranolol used to interfere with the reconsolidation of a recalled traumatic memory, so as to reduce its strength over time. This clinical trial will evaluate the effectiveness and cost-effectiveness of reconsolidation blockade compared to treatment as usual. The study involves four assessments: pre- and post-treatment and 13 weeks and 1 year follow up. The outcome measures include: PTSD symptoms, socioeconomic variables, quality of life and social functioning measures. The investigators hypothesize that all patients will improve. However, patients receiving reconsolidation blockade will recover faster than treatment as usual. Finally, investigators hypothesize that reconsolidation blockade will be well accepted both by the professionals and the patients.