OBJECTIVE:

Using the DSM-IV diagnostic criteria for acute stress disorder, the authors examined whether the acute psychological effects of being a bystander to violence involving mass shootings in an office building predicted later posttraumatic stress symptoms.

METHOD:

The participants in this study were 36 employees working in an office building where a gunman shot 14 persons (eight fatally). The acute stress symptoms were assessed within 8 days of the event, and posttraumatic stress symptoms of 32 employees were assessed 7 to 10 months later.

RESULTS:

According to the Stanford Acute Stress Reaction Questionnaire, 12 (33%) of the employees met criteria for the diagnosis of acute stress disorder. Acute stress symptoms were found to be an excellent predictor of the subjects' posttraumatic stress symptoms 7-10 months after the traumatic event.

CONCLUSIONS:

These results suggest not only that being a bystander to violence is highly stressful in the short run, but that acute stress reactions to such an event further predict later posttraumatic stress symptoms.