A chlorine gas leak interrupted the annual furry convention Midwest FurFest Sunday morning as the Hyatt Regency O'Hare at in Rosemont, Illinois, evacuated the hotel at 1:10 a.m. following reports of a chemical odor. First responders determined the odor to be a high level of chlorine gas, which police believe was intentionally caused.

Rosemont police stated the manner the substance was released, consistent with powdered chlorine, "suggests an intentional act." Police are investigating the incident as a criminal matter.

Hazmat teams found the source of the chlorine in a stairwell on the ninth floor of the Hyatt Regency O'Hare. After evacuating, 19 people complained of nausea and dizziness and were then transported to local hospitals. Hyatt Regency O'Hare stated some of those individuals were released by later Sunday morning.