Midwest FurFest's hotel was evacuated for several hours and nineteen people were hospitalized after what appears to be an intentional release of chlorine gas.

A broken plain glass jar containing a white powder was found in the ninth floor stairwell after reports from room 963 of a strong chlorine smell that forced the occupants onto the balcony.

A standard "box alarm" at 1:03 AM was quickly elevated to a hazardous materials and third-alarm emergency response. The adjoining convention center was used to house attendees until the area was made safe, with the all-clear sounded at 4:21 AM.

Additional sources: Chicago Tribune - Chicago Sun Times - ABC 7 (video)