A massive leak of liquefied chlorine gas created a dangerous cloud of poison gas over the city of Henderson, Nevada, in the early morning hours of May 6, 1991. Over 200 persons were examined at a local hospital for respiratory distress caused by inhalation of the chlorine and approximately 30 were admitted for treatment. Approximately 700 individuals were taken to shelters. It is estimated that from 2,000 to 7,000 individuals were taken elsewhere.