(CBS) — A chemical leak forced an evacuation of a hotel in Rosemont hosting a furry convention and sent 19 to the hospital.

The third alarm leak at the Hyatt Regency O’Hare happened right in the middle of the annual Midwest Furfest Convention, forcing people to evacuate the center in full costume. Authorities investigating the leak say it is consistent with an intentional act and police are investigating it as a crime.

Several witnesses say the leak was reported on either the 9th or 10th floor of the hotel. One woman says chlorine could be smelled on both floors.

Ambulances from surrounding suburbs were on scene to take people to area hospitals.