A study of the psychological consequences in overseas volunteers who witnessed the 1994 Rwandese genocide shows that witnessing a humanitarian catastrophe can induce severe Post Traumatic Stress Disorder (PTSD) symptoms. A brief group intervention attenuates the level of these symptoms. The efficacy of this intervention is discussed.
Sydor, G., & Philippot, P. (1996). [Post-traumatic stress symptoms: Prevalence and secondary prevention intervention after a humanitarian catastrophe.]. Revue Européenne de Psychologie Appliquée, 46(4), 269-276. https://hdl.handle.net/2078.5/64361 (Original work published 1996)