RESUMEN
Internal emergencies can occur at any time and location in a hospital. Planning, training, and exercises can prepare personnel to respond effectively to internal emergency situations. All hospital staff should be trained to recognize an internal incident and activate the hospital emergency management system. Maintaining the health and safety of patients, employees, and visitors is paramount. Training and exercises also encourage staff to act with competence and confidence during an untoward incident to mitigate or avert possible catastrophe. This article describes an incident in which 12 hospital employees presented to the emergency department after exposure to a potent pulmonary irritant gas, chlorine, following an unfortunate accident. These cases are used to illustrate how planning, training, and exercises assisted health care personnel in responding to a potentially catastrophic internal emergency.