Chlorine gas sickened several people and forced the evacuation of thousands of guests from a suburban Chicago hotel early Sunday, including many in animal costumes for a convention. Nineteen people were treated at hospitals.

Within hours, emergency workers decontaminated the Hyatt Regency O'Hare. Six-foot-tall rabbits, foxes, and dragons poured into the lobby. A few thousand people were at the Midwest FurFest, celebrating animals that are anthropomorphic through art, performance, and literature. The source of the gas was apparently chlorine powder left in a ninth-floor stairwell, according to the Rosemont Public Safety Department. Investigators believe the gas was created intentionally and are treating the incident as a criminal matter. - AP